I spray foamed my Florida attic and it cut AC bills by about 50%. Plus variable speed AC always runs on low speed now and the house is much more comfortable.
I was going to ask if this is something that can be done in a warm climate like Florida. We have a vented attic and it gets unbearably hot up there in the summer.
A study recently done in South Carolina showed that open cell foam can accumulate moisture that could potentially cause structural issues for roof sheathing. The researchers speculated that exterior moisture (dew or rain) between the roof shingles is forced into the roof sheathing by inward solar vapor drive. Another study’s computer model indicated that open-cell foam insulation is riskier than closed-cell foam in all US climate zones. Just something to think about. Nice video
regopit44 Is there any study with evidence of exterior vapor drive making it thru the roof system? I would like to Closed cell is by far a superior product to open cell when it comes to moisture concerns. The reason ins most installer dont install open cell to code. If a vapor barrier is installed and the proper R values are reached you should not see moisture getting thru to the roof deck.
Open cell foam absorbs moisture. Closed cell is its own vapor barrier. It will not absorb moisture. If any moisture got under those shingles and onto the sheathing, the sun would evaporate it rather quickly.
in many states and in Canada, you can't leave spray foam "visible" from the inside. You have to put a fire-retardant in front of it, like a gypsum board or spray a special sort of concrete made specifically for that purpose. But spray foam is by far the best insulation from my point of view.
@@ConcordCarpenter How do homeowners deal with roof leaks if there is only spray foam? Have you seen anyone create an airgap and then use spray foam behind it?
@@CarnivoreCris this is one of the reasons why I’m leaning away from spray foam. I still want the conditioned attic, but I don’t want to seal up the roof deck because that’s where water is going to leak in.
Can you convert a vented attic into an encapsulated attic? Should you worry about “roof leaks”? I saw ok other videos talking about closed cell foam hiding roof leaks from asphalt shingle roof
You can, and you should always be careful for roof leaks. I always suggest installing a new 30 year roof with a redundant layer of ice and water shield under it
We are building a new home, and our roofer is stating that the attic needs to be vented even though we want to keep it inside the thermal envelope. He said the shingles will peel and deteriorate much quicker if there is no air circulation(ie through soffit and ridge venting) in the attic space? Thoughts?
You shouldn’t insulate the roof deck with spray foam. It only solves 10-15% of specific cases. In both cold/snow climates, and warm/mixed damp climates it can crest issues that are far worse. You should have the mechanical systems inside the conditioned envelope of the house, but the best solution is to still vent the roof deck. This prevents the condensation plane from being on the underside of the roof sheathing in humid climates and prevents ice dams in cold snow climates. Vent the roof deck and include the hvac/mechanical systems in the conditioned envelope. If insulating the roof deck, insulate above the roof sheathing outlined in building science “the perfect wall”. The best is to vent the roof deck with a conditioned attic with the hvac inside the conditioned envelope.
Get this: my father is a retired UBC Carpenter, with lots of experience on commercial and industrial jobs. He and my mother built their own log cabin and moved in ca. 1975. The house is beautiful, but in the summer it is a horrible heat and humidity trap. The attic is undeveloped and resembles the house you illustrated in this video. (Insulation in the floor, bare inside panels for the peak, ridge vent, etc. My parents built it this way, out-of-pocket, in the early 70s. My mouth hung open as I watched this video. I wonder if there is a way to adapt their house as you suggest...
This really is only part of the solution and to encapsulate the attic this way has more challenges and potential expensive hazards. The best method does NOT put spray foam on the underside of the roof deck. Instead it leaves a gap and uses a combination of a radiant barrier on the edge of the rafters followed by either foam board or netting and spray foam. Leaving the gap all the way along the roof in the rafter space the roof can still breath and dry if there is a leak but also prevents ice dams. Note you must allow ventilation at the gables or top of the roof to allow hot summer air to leave. If you spray directly on the roof, especially with open cell foam if the roof should leak it is unable to dry and will do greater damage before discovery. Also any roof deck repairs will also require repair if the underlying spray foam increasing cost and hassle. In addition with the radiant barrier radiant heat is repelled lowering temps and cooling costs. If in a cold climate the underside of the foam board can be sprayed with insulating foam and a second internal radiant barrier added if desired to bounce heat back into your home.
I’ve seen roofs that are sprayed tight like that and the roof deck rotted out completely. They sprayed to prevent moisture leaks and ended up with a bigger problem
Aces High The attic never gets hot in the Summer because it is encapsulated while warm air rises it never gets that hot Your point of a roof leak is valid and is probably the only negative to spray foam. Normal thinking would tell you that having enough airflow or ventilation would solve this problem. That is not the case for every home. Some homes are leakier than others. Some homes do not have proper air sealing on the floor of the attic. Some homes have HVAC equipment in the attic which leaks. (All HVAC units leak by design) there are a myriad of reasons for moisture buildup in the attic. The most common is air leaks allowing moisture to travel up into the attic space and condense on the cold surface of the roof deck. This is a very common problem in climate zone five here in New England. I see 2 to 3 cases a week in my travels were this is extremely evident. Typically it requires mold remediation and dehumidification to dry the area. An application of a closed cell spray foam can prevent the moisture from getting to the roof deck and condensing. Most folks would believe that adding ventilation would solve this problem ( which in some cases can) but that is not always the case. Closed cell spray foam is the only solution that we have found for this particular problem. There is a lot involved such as removal of the existing insulation, mold remediation and/or cleanup. There are a lot of other contributing factors that can cause this, such as bath fans not being connected properly. Those same bath fans being vented in the soffit and not properly ejecting The steam outside. Closed cell spray foam if installed on the roof deck is a one stop shop repair that will solve this issue for almost all attics.
Aces High A majority of roofs in this country are foam. (commercial flat roofs) Putting foam on the roof deck keeps the solar radiation from getting in and thus lowers the indoor attic temperature. Open cell in a Zone 5 where we are located requires a vapor barrier. No need for venting as moisture should not be making it to the roof deck. Stopping heat loss is the only way to prevent ice dams. No melt no water to create ice. Why are we to assume a roof will leak if were talking best practices? A roof typically fails due to a rusty fastener which is caused by condensation buildup which removes the zinc from the fastener and allows it to rust and fail. When a roof deck is foamed this does not happen hence lessening the likelihood of a leak. Also any roof deck repairs will also require repair if the underlying spray foam increasing cost and hassle. Typical repairs with open cell are not much different from a regular repair. You remove the damaged wood and replace. Open cell is hydrophobic and will dry out. If someone is doing demo and damages the foam or it gets ripped out during removal (not common) then yes there will be an added cost to repair. The same as a cellulose roof or a fiberglass roof where the product would be damaged from water. Also mold cant grow on foam plastics. However it can grow on fiber products. Radiant barriers are not going to prevent the ice damage we see here in Zone 5 nor will it be very cost friendly from a budget standpoint. In my 18 years I have yet to see one home where this was used. Let alone effective.
Christopher Gruenwald well it will rot your sheeting if you don’t address the leak, but at least you will know you have a leak so you can fix it before it rots your wood
@@21gonza21 I wonder if creating an airgap with a dimple mat product like DELTA-FL and spray foam afterwards would work. I want to spray foam my roof deck but trying to figure out how to deal with leaks.
I’ve spray foamed 3 of my homes. You have to use open cell on roof decks. No you won’t have condensation and you will be able to detect any roof leaks. Not the case with closed cell. Open cell on roof decks!!!!!
Question, i own a 1780 home in new england where i have no soffit due to the age of the house. I do have a ridge vent and 2 windows on each side. I'm building a living area at the attic area. I'm going with cathedral ceilings. I see people insulate the attic ceiling. My structural engineer said not to do that. Is she right or wrong? I wouldn't insulate the entire attic ceiling. Just maybe 5 ft of it and i'll have a gap above where the ridge vent sits.
There are limitations to this. With an insulated roof deck temperatures can get really high on the roof deck and cause heat damage to certain roofing materials, and ice dams. Also, certain roofing systems need ventilation on the underside of the roof deck to allow for moisture control, like wood shakes or shingles. A way to circumvent this is to have a cold weather hybrid roof deck, where a solid sheathing is used, spray foam can be applied to the bottom of this, and then having vertical spacing boards on top of the roof trusses, then put nailing strips horizontally on top of the spacers. This allows for protection from racking, hurricane proof and earthquake proof with the solid deck, and also a spaced sheathing to allow moisture to be removed by venting between the two deck spaces, prevents overheating of the upper roof deck and allows for insulation directly against the solid deck, where it is easy to apply. The total cost above a standard deck on my house was about $400, a paltry sum for most houses. I've seen many, many shake roofs fail prematurely because of inadequate drying potential as people switch to solid sheathing on the roof deck, especially with tar paper under the shakes. This wasn't a problem with traditional installation over spaced sheathing, but many areas now require a solid deck for stability.
Can I insulate the ceiling for sound after the roof pan has been sprayed with 6 inches of closed cell? My mechanicals will be in the attic space and T&G on the underside of the living area. I get sound transmission from heavy rains, so I thought to deadened that with 3 inch fiberglass, and hopefully no moisture issues
Will this stop my neighbors cigarette smoke from entering my home? I have an open vented attic and during the night my house fills with cigarette smoke, the open attic is the only thing I can think is the cause?
Unrelated attic question. I live in the partial basement of a house that comes out of a Small hill and becomes another section of the dwelling with a roof. It has wood soffits that are covered in metal. As far as i van tell there is no ventilation There are a total of 5 4 ft lights recessed into the ceiling inside. My place smells like an attic. Is none venting of the soffits the reason for this smell inside?
Usually a Heat Recovery Ventilator or an Energy Recovery Ventilator would be installed. It's a system that cycles fresh air into the house and removes stale air for 20 minutes every hour. They are typically called HRV and ERV respectively.
Thank you!! I have a cape with nasty old fiberglass batting that is 2 inches thick in my attic space. I have wanted to remove that and do spray foam so we can actually use some of the space. Our furnace is oil and in the basement and we use portable AC units. Do you recommend open or closed cell foam for a New England home?
@@HarmonsHarbor Hi!! We have not yet done our cape. I am searching for a reputable company in Massachusetts to take care of that for me. Please let me know if you know of anyone in the Worcester/Framingham area that does closed cell. My hubby and I love Maine!! We are looking to retire there someday. Good luck on your cape!! Hope it stays nice and toasty in the winter and cool and breezy in the summer! (Breezy with the windows open of course😁)
@@m.k.1543 The company I’m going with uses Gaco, which has a GreenGuard Gold certification. My house is a one-story Cape with less than 7ft walls, so I’m having it all opened up to make cathedral ceilings throughout. Spray foam has to be used here because of added room additions and there’s no way to ventilate a lot of the old rafter bays. The soffits are gone. Spray Jones has a great TH-cam channel with lots of information, if you’re interested.
Correct me if I'm wrong but isn't it best practice to leave a 1" air space with spray foam, to help keep it on the warm side, like we do with our batt type insulation? My understanding is condensation and execessive moisture can come from the foam being right against the roof sheathing. Cheers
Michael D If open cell spray foam is applied to the roof deck and a vapor barrier is applied like as seen in the video (maybe we should do a video on the vapor barrier) Then no venting is required. If the require R value is installed there should be no ability for condensation to happen. Venting is to remove heat and humidity/moisture. When the HVAC is not tasked with outdoor humidity and properly controlled there is much less humidity in a home to deal with. This also lessens the potential for condensation and vapor drive making its way to the roof deck. In conclusion open cell spray foam is a great product and cost savings over closed cell when installed properly. Closed cell is a more expensive product that has a vapor barrier, thermal barrier and air barrier all in one. Which is why the industry is starting to spray more closed cell today then we have in the last 18 years.
@@ConcordCarpenter what about when you inevitably have a roof leak? That water is going to be trapped. I think this is what the original poster was asking about.
I have a fully encapsulated house with opencell foam, I'm having a problem with attic humidity. Would leaky flex ducts at plenum or registers cause this? My garage attic has the thin cardboard sheathing with sprayfoam behind that to separate the 2 attics. Is moisture going thru the sheathing and foam into my conditioned attic? Thanks for your insight.
@@ConcordCarpenter Yes the baths have cheap builder exhaust fans, yesterday I found that out they were blowing into attic at spots, So I sealed both up with foil tap. I'm going to replace with better Panasonic fans real soon. My builder doesn't spray the attached garages. I have a pulldown attic entrance in garage then there is a solid core door to walk into conditioned attic. All my outside and walls that butt up to garage are 2x6 and spray foamed. Wish I could send you a pic.
I don't know if you ever found your answer but open cell foam insulation does not provide a fully conditioned attic unless all cracks, gaps, penetrations and such were sealed before spraying. To eliminate the humidity in the attic you need some sort of air exchanger or condition the space with a supply and return so that the hvac system can remove the humidity.
@@christopherhorne8665 Hello, A while back I found where the installer missed an area by the wall separating the garage from conditioned attic. I bought a 2part kit and sprayed that missed area and whola humidity dropped to almost the same as inside. I have 2x6 outside walls, all spray foam including attic. $100 or less electric bill in 100+ degree +high humidity north Texas in July, August, September.. I will eventually install a good dehumidifier and plumb it into supply plenum to get around 50 Rh or lower..
There won’t be condensation as the spray foam is air impervious. Also, you need to use the open cell on roof decks. In case there is a leak, it can be seen and detected. Closed cell won’t allow you to see the leak.
IRBC 302.11(4) requires plugging those holes, if not for air leakage then for fireblocking. I think most developed nations have adopted some form of building codes to prevent this sort of shoddy workmanship.
Don't let your plumbers run any water lines under concrete unless inside a 2" conduit. And make them put a shut off in the wall where it enters the house. Just sayin.😎😁
Doesn’t the HVAC work harder because there is more volume to condition? Is that offset by the savings from air sealing? What if you air seal the floor of the attic instead?
@@ConcordCarpenter well in florida you can spray the attic but almost all the homes are block with 3/4'' furring and they mostly use fi-foil rolls which are garbage. so i would spray the attic, do an aluminum roof, then 3/4 insulfoam sheets on the walls
@@chadhensley3689 They wrote, “Recent data collected from a test facility in Charleston, SC (Miller et al. 2013) revealed very interesting summertime trends in attic humidity for a sealed attic as compared to the conventionally ventilated attics. … [In a sealed attic insulated with open-cell spray foam,] peaks in measured relative humidity from two different sensors in the sealed attic showed values in excess of 80%-90%, and occasionally saturated air (i.e., 100%) occurred around solar noon. In other words, the moisture content in the sealed attic was consistently 80%-100% RH from solar noon to around 6 p.m. for the seven contiguous days.” source: www.greenbuildingadvisor.com/article/open-cell-spray-foam-and-damp-roof-sheathing
@@markhooker8520 I have been experiencing this in my Texas foamed house. Humidity in attic is super high as well as around 60% inside house. What can I do??
@@mateo-6965 Well first I'll note I disagree with Raul Torres above. He says don't use closed cell foam in an attic. What I've read is the opposite. Here are the considerations: 1. Closed-cell foam is vapor impermeable. That means water vapor won't enter it and migrate through it to your roof deck. 2. Open-cell foam IS vapor-permeable; that is the problem... because water vapor migrates up through it, hits the roof deck and (if roof deck is cold) condenses and begins the rot cycle. 3. Additionally, if you have cold things in your attic, you can expect condensation to appear there. Regarding things you can do: 1. Make sure all sources of humidity sources in your home are properly vented and that people use those vents. Examples: kitchen range hood, bathroom vents, laundry room. 2. If practical, stop air leaking from the living space in your home into the attic. BTW: stopping these types of air leaks also is the most high impact thing you can do to increase comfort and energy efficiency of the home. Finally, another source of humidity in most homes is the basement slab. Soil under ground is always at 100% humidity and concrete is vapor permeable... so there is always going to be humidity coming into a basement, then moving up.
@@markhooker8520 I admit we hardly use the bath, laundry fans ,or gas cooktop venthood. They are pretty loud cheapy builder grade. I'm goin to replace with quieter models here soon. Also do you think humidity is going thru my uninsulated garage attic thru the foam wall? It only has the thin cardboard type sheathing then around 8 inches behind that into my conditioned attic. Thanks again!
I spray foamed my Florida attic and it cut AC bills by about 50%. Plus variable speed AC always runs on low speed now and the house is much more comfortable.
I was going to ask if this is something that can be done in a warm climate like Florida. We have a vented attic and it gets unbearably hot up there in the summer.
Glenn Holcomb what type roof/attic hvac set up would you recommend for a new Florida house
A study recently done in South Carolina showed that open cell foam can accumulate moisture that could potentially cause structural issues for roof sheathing. The researchers speculated that exterior moisture (dew or rain) between the roof shingles is forced into the roof sheathing by inward solar vapor drive. Another study’s computer model indicated that open-cell foam insulation is riskier than closed-cell foam in all US climate zones. Just something to think about. Nice video
regopit44 interesting, can you please share links to those studies?
regopit44 Is there any study with evidence of exterior vapor drive making it thru the roof system? I would like to Closed cell is by far a superior product to open cell when it comes to moisture concerns. The reason ins most installer dont install open cell to code. If a vapor barrier is installed and the proper R values are reached you should not see moisture getting thru to the roof deck.
Open cell foam absorbs moisture. Closed cell is its own vapor barrier. It will not absorb moisture. If any moisture got under those shingles and onto the sheathing, the sun would evaporate it rather quickly.
in many states and in Canada, you can't leave spray foam "visible" from the inside. You have to put a fire-retardant in front of it, like a gypsum board or spray a special sort of concrete made specifically for that purpose.
But spray foam is by far the best insulation from my point of view.
yes - same
yes = the spray foam in this video was painted with fire retardant spray
There is CC foam that has the fire retardant in it already.
@@ConcordCarpenter How do homeowners deal with roof leaks if there is only spray foam? Have you seen anyone create an airgap and then use spray foam behind it?
@@CarnivoreCris this is one of the reasons why I’m leaning away from spray foam. I still want the conditioned attic, but I don’t want to seal up the roof deck because that’s where water is going to leak in.
Can you convert a vented attic into an encapsulated attic? Should you worry about “roof leaks”? I saw ok other videos talking about closed cell foam hiding roof leaks from asphalt shingle roof
You can, and you should always be careful for roof leaks. I always suggest installing a new 30 year roof with a redundant layer of ice and water shield under it
Thanks for the vids bro, your videos help out a lot!!
We are building a new home, and our roofer is stating that the attic needs to be vented even though we want to keep it inside the thermal envelope. He said the shingles will peel and deteriorate much quicker if there is no air circulation(ie through soffit and ridge venting) in the attic space? Thoughts?
I would like an answer to this too.
Out of curiosity, what did you end up doing here? Was the plan for your attic meant as livable space or unlivable?
You shouldn’t insulate the roof deck with spray foam. It only solves 10-15% of specific cases. In both cold/snow climates, and warm/mixed damp climates it can crest issues that are far worse.
You should have the mechanical systems inside the conditioned envelope of the house, but the best solution is to still vent the roof deck. This prevents the condensation plane from being on the underside of the roof sheathing in humid climates and prevents ice dams in cold snow climates.
Vent the roof deck and include the hvac/mechanical systems in the conditioned envelope.
If insulating the roof deck, insulate above the roof sheathing outlined in building science “the perfect wall”.
The best is to vent the roof deck with a conditioned attic with the hvac inside the conditioned envelope.
Get this: my father is a retired UBC Carpenter, with lots of experience on commercial and industrial jobs. He and my mother built their own log cabin and moved in ca. 1975. The house is beautiful, but in the summer it is a horrible heat and humidity trap. The attic is undeveloped and resembles the house you illustrated in this video. (Insulation in the floor, bare inside panels for the peak, ridge vent, etc. My parents built it this way, out-of-pocket, in the early 70s. My mouth hung open as I watched this video. I wonder if there is a way to adapt their house as you suggest...
wingsley sure is
This really is only part of the solution and to encapsulate the attic this way has more challenges and potential expensive hazards.
The best method does NOT put spray foam on the underside of the roof deck. Instead it leaves a gap and uses a combination of a radiant barrier on the edge of the rafters followed by either foam board or netting and spray foam.
Leaving the gap all the way along the roof in the rafter space the roof can still breath and dry if there is a leak but also prevents ice dams. Note you must allow ventilation at the gables or top of the roof to allow hot summer air to leave.
If you spray directly on the roof, especially with open cell foam if the roof should leak it is unable to dry and will do greater damage before discovery. Also any roof deck repairs will also require repair if the underlying spray foam increasing cost and hassle.
In addition with the radiant barrier radiant heat is repelled lowering temps and cooling costs. If in a cold climate the underside of the foam board can be sprayed with insulating foam and a second internal radiant barrier added if desired to bounce heat back into your home.
Nice
I’ve seen roofs that are sprayed tight like that and the roof deck rotted out completely. They sprayed to prevent moisture leaks and ended up with a bigger problem
Ben-jam-n like what?
Aces High The attic never gets hot in the Summer because it is encapsulated while warm air rises it never gets that hot
Your point of a roof leak is valid and is probably the only negative to spray foam.
Normal thinking would tell you that having enough airflow or ventilation would solve this problem. That is not the case for every home. Some homes are leakier than others. Some homes do not have proper air sealing on the floor of the attic. Some homes have HVAC equipment in the attic which leaks. (All HVAC units leak by design) there are a myriad of reasons for moisture buildup in the attic. The most common is air leaks allowing moisture to travel up into the attic space and condense on the cold surface of the roof deck. This is a very common problem in climate zone five here in New England. I see 2 to 3 cases a week in my travels were this is extremely evident. Typically it requires mold remediation and dehumidification to dry the area. An application of a closed cell spray foam can prevent the moisture from getting to the roof deck and condensing. Most folks would believe that adding ventilation would solve this problem ( which in some cases can) but that is not always the case. Closed cell spray foam is the only solution that we have found for this particular problem. There is a lot involved such as removal of the existing insulation, mold remediation and/or cleanup. There are a lot of other contributing factors that can cause this, such as bath fans not being connected properly. Those same bath fans being vented in the soffit and not properly ejecting The steam outside. Closed cell spray foam if installed on the roof deck is a one stop shop repair that will solve this issue for almost all attics.
Aces High
A majority of roofs in this country are foam. (commercial flat roofs) Putting foam on the roof deck keeps the solar radiation from getting in and thus lowers the indoor attic temperature. Open cell in a Zone 5 where we are located requires a vapor barrier. No need for venting as moisture should not be making it to the roof deck.
Stopping heat loss is the only way to prevent ice dams. No melt no water to create ice.
Why are we to assume a roof will leak if were talking best practices? A roof typically fails due to a rusty fastener which is caused by condensation buildup which removes the zinc from the fastener and allows it to rust and fail. When a roof deck is foamed this does not happen hence lessening the likelihood of a leak. Also any roof deck repairs will also require repair if the underlying spray foam increasing cost and hassle. Typical repairs with open cell are not much different from a regular repair. You remove the damaged wood and replace. Open cell is hydrophobic and will dry out. If someone is doing demo and damages the foam or it gets ripped out during removal (not common) then yes there will be an added cost to repair. The same as a cellulose roof or a fiberglass roof where the product would be damaged from water. Also mold cant grow on foam plastics. However it can grow on fiber products.
Radiant barriers are not going to prevent the ice damage we see here in Zone 5 nor will it be very cost friendly from a budget standpoint. In my 18 years I have yet to see one home where this was used. Let alone effective.
I have an issue only with the summer heat here in Vegas. I thought about sealing the attic and adding a mini split. Would that be a good idea?
yes
Like the New Intro!
Please do a 1/2" impact comparison!
How would you know when you have a roof leak? Won’t it rot the roof sheeting ??
Yeah roof leaks rot the sheeting even in a ventilated attic. Why is your roof leaking? The insulation isn’t the problem, the roof is.
Christopher Gruenwald well it will rot your sheeting if you don’t address the leak, but at least you will know you have a leak so you can fix it before it rots your wood
@@21gonza21 I wonder if creating an airgap with a dimple mat product like DELTA-FL and spray foam afterwards would work. I want to spray foam my roof deck but trying to figure out how to deal with leaks.
@@christophergruenwald5054 open cell foam allows water through but not air, as long as its 5.5" thick.
I’ve spray foamed 3 of my homes. You have to use open cell on roof decks. No you won’t have condensation and you will be able to detect any roof leaks. Not the case with closed cell. Open cell on roof decks!!!!!
Any tips for a diy on this? Or how to tell what kind of heating system i have?
Question, i own a 1780 home in new england where i have no soffit due to the age of the house. I do have a ridge vent and 2 windows on each side. I'm building a living area at the attic area. I'm going with cathedral ceilings. I see people insulate the attic ceiling. My structural engineer said not to do that. Is she right or wrong? I wouldn't insulate the entire attic ceiling. Just maybe 5 ft of it and i'll have a gap above where the ridge vent sits.
There are limitations to this. With an insulated roof deck temperatures can get really high on the roof deck and cause heat damage to certain roofing materials, and ice dams.
Also, certain roofing systems need ventilation on the underside of the roof deck to allow for moisture control, like wood shakes or shingles.
A way to circumvent this is to have a cold weather hybrid roof deck, where a solid sheathing is used, spray foam can be applied to the bottom of this, and then having vertical spacing boards on top of the roof trusses, then put nailing strips horizontally on top of the spacers.
This allows for protection from racking, hurricane proof and earthquake proof with the solid deck, and also a spaced sheathing to allow moisture to be removed by venting between the two deck spaces, prevents overheating of the upper roof deck and allows for insulation directly against the solid deck, where it is easy to apply. The total cost above a standard deck on my house was about $400, a paltry sum for most houses.
I've seen many, many shake roofs fail prematurely because of inadequate drying potential as people switch to solid sheathing on the roof deck, especially with tar paper under the shakes. This wasn't a problem with traditional installation over spaced sheathing, but many areas now require a solid deck for stability.
Macks Power have you used Cedar Breather?
@@ConcordCarpenter Yes, in the bottom 36" of the roof where a solid deck is required under the shakes.
Macks Power interesting so I’m guessing you install over skip sheathing?
@@ConcordCarpenter sort of. I use a hybrid similar to a cold weather deck.
Solid sheathing then 2x4 vertical spacers, 1x4 spaced sheathing on top.
Can I insulate the ceiling for sound after the roof pan has been sprayed with 6 inches of closed cell?
My mechanicals will be in the attic space and T&G on the underside of the living area. I get sound transmission from heavy rains, so I thought to deadened that with 3 inch fiberglass, and hopefully no moisture issues
What type of insulation do you recommend in Florida, hot and humid climate, one story home with hvac in the attic?
Will this stop my neighbors cigarette smoke from entering my home? I have an open vented attic and during the night my house fills with cigarette smoke, the open attic is the only thing I can think is the cause?
Makes it a lot harder to diagnose and repair any roof leaks
luke hunter agreed
Unrelated attic question.
I live in the partial basement of a house that comes out of a Small hill and becomes another section of the dwelling with a roof. It has wood soffits that are covered in metal. As far as i van tell there is no ventilation
There are a total of 5 4 ft lights recessed into the ceiling inside.
My place smells like an attic. Is none venting of the soffits the reason for this smell inside?
Smells like fiberglass?
House does the building fabric breath if totally sealed airtight?
Usually a Heat Recovery Ventilator or an Energy Recovery Ventilator would be installed.
It's a system that cycles fresh air into the house and removes stale air for 20 minutes every hour.
They are typically called HRV and ERV respectively.
In the UK this stuff burns as well
@@juliansaunders6163 Pretty much everything burns. At the right temperature some things actually explode.
How do I know if I should be using open cell or closed cell foam in my attic?
If you want to error on the side of caution, use closed cell
My attic is encapsulated. However, it is a flu that doesn’t have insulation between the roof and the flu. What do you recommend? Thanks
Angel Rivera One solution is to wrap it in Rockwool sprayed in place.
Thank you!! I have a cape with nasty old fiberglass batting that is 2 inches thick in my attic space. I have wanted to remove that and do spray foam so we can actually use some of the space. Our furnace is oil and in the basement and we use portable AC units. Do you recommend open or closed cell foam for a New England home?
Closed cell! Have you done your Cape yet? I have a Cape in Maine and I’m doing mine as well.
@@HarmonsHarbor Hi!! We have not yet done our cape. I am searching for a reputable company in Massachusetts to take care of that for me. Please let me know if you know of anyone in the Worcester/Framingham area that does closed cell.
My hubby and I love Maine!! We are looking to retire there someday. Good luck on your cape!! Hope it stays nice and toasty in the winter and cool and breezy in the summer! (Breezy with the windows open of course😁)
@@HarmonsHarbor lol. I just realized that Concord Carpenter is in my area. Derrrr🤪🙄. I think I might just call him. 😊
@@m.k.1543 The company I’m going with uses Gaco, which has a GreenGuard Gold certification. My house is a one-story Cape with less than 7ft walls, so I’m having it all opened up to make cathedral ceilings throughout. Spray foam has to be used here because of added room additions and there’s no way to ventilate a lot of the old rafter bays. The soffits are gone. Spray Jones has a great TH-cam channel with lots of information, if you’re interested.
@@HarmonsHarbor thank you!!!
Correct me if I'm wrong but isn't it best practice to leave a 1" air space with spray foam, to help keep it on the warm side, like we do with our batt type insulation? My understanding is condensation and execessive moisture can come from the foam being right against the roof sheathing.
Cheers
Michael D it’s not needed, this is an unvented attic assembly. Completely encased in a thermal envelope. Venting is not needed
Michael D If open cell spray foam is applied to the roof deck and a vapor barrier is applied like as seen in the video (maybe we should do a video on the vapor barrier) Then no venting is required. If the require R value is installed there should be no ability for condensation to happen. Venting is to remove heat and humidity/moisture. When the HVAC is not tasked with outdoor humidity and properly controlled there is much less humidity in a home to deal with. This also lessens the potential for condensation and vapor drive making its way to the roof deck.
In conclusion open cell spray foam is a great product and cost savings over closed cell when installed properly. Closed cell is a more expensive product that has a vapor barrier, thermal barrier and air barrier all in one. Which is why the industry is starting to spray more closed cell today then we have in the last 18 years.
@@ConcordCarpenter what about when you inevitably have a roof leak? That water is going to be trapped. I think this is what the original poster was asking about.
I have a fully encapsulated house with opencell foam, I'm having a problem with attic humidity. Would leaky flex ducts at plenum or registers cause this? My garage attic has the thin cardboard sheathing with sprayfoam behind that to separate the 2 attics. Is moisture going thru the sheathing and foam into my conditioned attic? Thanks for your insight.
Mateo PW yes, are your showers vented? The garage ceiling sound suspect - thought you said it was all foamed?
@@ConcordCarpenter Yes the baths have cheap builder exhaust fans, yesterday I found that out they were blowing into attic at spots, So I sealed both up with foil tap. I'm going to replace with better Panasonic fans real soon.
My builder doesn't spray the attached garages. I have a pulldown attic entrance in garage then there is a solid core door to walk into conditioned attic. All my outside and walls that butt up to garage are 2x6 and spray foamed. Wish I could send you a pic.
I don't know if you ever found your answer but open cell foam insulation does not provide a fully conditioned attic unless all cracks, gaps, penetrations and such were sealed before spraying. To eliminate the humidity in the attic you need some sort of air exchanger or condition the space with a supply and return so that the hvac system can remove the humidity.
@@christopherhorne8665 Hello, A while back I found where the installer missed an area by the wall separating the garage from conditioned attic. I bought a 2part kit and sprayed that missed area and whola humidity dropped to almost the same as inside. I have 2x6 outside walls, all spray foam including attic. $100 or less electric bill in 100+ degree +high humidity north Texas in July, August, September.. I will eventually install a good dehumidifier and plumb it into supply plenum to get around 50 Rh or lower..
Have you had issues with off gassing of spray foam rotting out hvac equipment yet? I have heard this can be a issue.
No - havnt heard of it
no
Cool thank you
Awesome
Won’t it rot the roofs plywood with all the condensation??
There won’t be condensation as the spray foam is air impervious. Also, you need to use the open cell on roof decks. In case there is a leak, it can be seen and detected. Closed cell won’t allow you to see the leak.
The value is negated by the fact that it is impossible to find someone to encapsulate an attic space properly.
IRBC 302.11(4) requires plugging those holes, if not for air leakage then for fireblocking.
I think most developed nations have adopted some form of building codes to prevent this sort of shoddy workmanship.
Macks Power fire locking is required, from one side- if you referring to the wire penetrations, they were fire blocked from below
The number one goal is to conserve energy, by conditioning the attic that’s another area to heat.
Done right - your not wasting energy
Cordeiro Woodworks the number one goal is condition with efficiency. You want to save money? Use newspapers inside the walls
Don’t you run a risk of roof rot with open cell foam?
John C no
Yes. See building science.
If I ever get to build my new house (6 months of rain delays so far), this is how I’m doing mine.
Don't let your plumbers run any water lines under concrete unless inside a 2" conduit. And make them put a shut off in the wall where it enters the house.
Just sayin.😎😁
Chris Gilliam Man Stuff Channel No, only drain lines are going under.
Doesn’t the HVAC work harder because there is more volume to condition? Is that offset by the savings from air sealing? What if you air seal the floor of the attic instead?
Termites?
Termites don’t touch spray foam
This and 3/4 insulfoam sheets
no spray foam
@@ConcordCarpenter well in florida you can spray the attic but almost all the homes are block with 3/4'' furring and they mostly use fi-foil rolls which are garbage. so i would spray the attic, do an aluminum roof, then 3/4 insulfoam sheets on the walls
Never use closed cell foam in the southern USA
Why?
@@chadhensley3689 They wrote, “Recent data collected from a test facility in Charleston, SC (Miller et al. 2013) revealed very interesting summertime trends in attic humidity for a sealed attic as compared to the conventionally ventilated attics. … [In a sealed attic insulated with open-cell spray foam,] peaks in measured relative humidity from two different sensors in the sealed attic showed values in excess of 80%-90%, and occasionally saturated air (i.e., 100%) occurred around solar noon. In other words, the moisture content in the sealed attic was consistently 80%-100% RH from solar noon to around 6 p.m. for the seven contiguous days.”
source: www.greenbuildingadvisor.com/article/open-cell-spray-foam-and-damp-roof-sheathing
@@markhooker8520 I have been experiencing this in my Texas foamed house. Humidity in attic is super high as well as around 60% inside house. What can I do??
@@mateo-6965
Well first I'll note I disagree with Raul Torres above. He says don't use closed cell foam in an attic. What I've read is the opposite. Here are the considerations:
1. Closed-cell foam is vapor impermeable. That means water vapor won't enter it and migrate through it to your roof deck.
2. Open-cell foam IS vapor-permeable; that is the problem... because water vapor migrates up through it, hits the roof deck and (if roof deck is cold) condenses and begins the rot cycle.
3. Additionally, if you have cold things in your attic, you can expect condensation to appear there.
Regarding things you can do:
1. Make sure all sources of humidity sources in your home are properly vented and that people use those vents. Examples: kitchen range hood, bathroom vents, laundry room.
2. If practical, stop air leaking from the living space in your home into the attic. BTW: stopping these types of air leaks also is the most high impact thing you can do to increase comfort and energy efficiency of the home.
Finally, another source of humidity in most homes is the basement slab. Soil under ground is always at 100% humidity and concrete is vapor permeable... so there is always going to be humidity coming into a basement, then moving up.
@@markhooker8520 I admit we hardly use the bath, laundry fans ,or gas cooktop venthood. They are pretty loud cheapy builder grade. I'm goin to replace with quieter models here soon.
Also do you think humidity is going thru my uninsulated garage attic thru the foam wall? It only has the thin cardboard type sheathing then around 8 inches behind that into my conditioned attic. Thanks again!
Nice video. I still prefer vented, unconditioned attics. Simpler and easy.
where do you live? Build?
@@ConcordCarpenter north east
So not insulated for a living area addon. hmmmmm. Gotta be expensive.
no more than doing the floor