What needs to be done before and after spray foam insulation?

[The One]

I'm getting my garage insulated with spray foam. All electrical work and plumbing will be done before hand. Do I need to seal up anything before the walls and ceiling are sprayed?

After do I need to seal up the spots where he will be unable to get? Such as were boards are sandwiched together by framed windows?

In the ceiling I am having him spray in 2" and then bring up the r-value with blown in (I haven't decided how high I want to go yet). Should I have him place planking on top of the spray foam before doing he does the blown in? I don't envision ever needing to go up there unless there's a roofing structural problem, but in that case I'd imagine the lack of planking would be the least of my worries.

 

[The One]

I forgot to add that I am putting in vent baffles before putting up the ceiling.

 

[Chris705]

Have a conversation with your spray foam contractor. My experience has been that they prepare for the spray, taping over electrical boxes etc. they may or may not foam around your windows. If you have inaccessible corners I would suggest drilling 1/2” holes at 48” to allow foam to be sprayed in them. Not sure that the foamer would install planking up in your attic area or not , again a question you could ask them. Or do it yourself keeping it above the level of your intended loose insulation.

 

[mcbane]

Before: make sure your fire insurance policy doesn't prohibit flammable insulation

 

[bobbyjean]

maybe you can add some support framing now for a platform type storage idea that will be used later-sounds easier than digging thru that blown in insulation...

 

[DWise]

Do you need to consider running any Ethernet, coax or Phone?

 

[Northislander]

I did flash and batt on my shop walls and ceiling. So didn't have to worry about this as i did most of the plumbing and all the wiring after the spray foam. But you have to secure everything well so the expanding foam doesn't push wiring or piping out of the stud cavtiy. Other than that the spray foam installers around here prep everything.

 

[Voi]

I forgot to add that I am putting in vent baffles before putting up the ceiling.

The baffles are going up between the top chords against the roof deck & then you're having the ceiling spray foamed? Or are is the spray foam going over the baffles?

 

[The One]

The baffles are going up between the top chords against the roof deck & then you're having the ceiling spray foamed? Or are is the spray foam going over the baffles?

The baffles are going up against the roof. The spray foam is going on the ceiling. The purpose of the baffles is to prevent the blown in insulation that I'm putting over top of the spray foam from falling down into the soffits.

My understanding is the there is no benefit of insulating the roof in my setup?

I bought the Provent baffles from Menards they're plastic sheet instead of the foam. I think they'll hold up a little better while installing.

 

[The One]

Do you need to consider running any Ethernet, coax or Phone?

My house isn't setup for that yet so in the meantime I am laying 2 extra conduit while I'm trenching for gas.

 

[The One]

I did flash and batt on my shop walls and ceiling. So didn't have to worry about this as i did most of the plumbing and all the wiring after the spray foam. But you have to secure everything well so the expanding foam doesn't push wiring or piping out of the stud cavtiy. Other than that the spray foam installers around here prep everything.

Are you able to expand on what prep they do?

The only thing going through my attic will be 1 wire for a light. Everything else will either go through the walls or over top of the walls (exposed electric for ease).

 

[The One]

Before: make sure your fire insurance policy doesn't prohibit flammable insulation

I talked to the insulator guy and he said that while it does burn when flame is directly applied it self extinguishes.

 

[Voi]

The baffles are going up against the roof. The spray foam is going on the ceiling.

Okay, I was pretty sure that's what you meant but sometimes the terms ceiling and underside of roof deck get used interchangeably.

The purpose of the baffles is to prevent the blown in insulation that I'm putting over top of the spray foam from falling down into the soffits.

I bought the Provent baffles from Menards they're plastic sheet instead of the foam. I think they'll hold up a little better while installing.

I'm not familiar with these baffles. I have heard of people spraying foam on their ceiling before blown-in and I think the possibility of the spray foam compressing the baffles to the point they're compromised is a concern. I've heard of people making their own baffles to prevent this. Maybe the Provent baffles are good enough, I don't know.

My understanding is the there is no benefit of insulating the roof in my setup?

There might be some benefit as far as air sealing but then you lose the benefits of a ventilated space and get none of the benefits of the extra space since you have a ceiling anyways.

Normally when spray foam is combined with fiberglass or cellulose one needs to maintain a ratio of r-value of foam to fiberglass. That ratio is particular to a climate zone and is to prevent condensation and freezing on the foam layer.

In your case I assume since the foam is going in first you won't have these issues but that is well beyond my expertise. I only responded to this thread after having read about issues with closed cell compressing ventilation baffles. You seem to be aware of this possibility.

 

[The One]

Okay, I was pretty sure that's what you meant but sometimes the terms ceiling and underside of roof deck get used interchangeably.



I'm not familiar with these baffles. I have heard of people spraying foam on their ceiling before blown-in and I think the possibility of the spray foam compressing the baffles to the point they're compromised is a concern. I've heard of people making their own baffles to prevent this. Maybe the Provent baffles are good enough, I don't know.



There might be some benefit as far as air sealing but then you lose the benefits of a ventilated space and get none of the benefits of the extra space since you have a ceiling anyways.

Normally when spray foam is combined with fiberglass or cellulose one needs to maintain a ratio of r-value of foam to fiberglass. That ratio is particular to a climate zone and is to prevent condensation and freezing on the foam layer.

In your case I assume since the foam is going in first you won't have these issues but that is well beyond my expertise. I only responded to this thread after having read about issues with closed cell compressing ventilation baffles. You seem to be aware of this possibility.

I appreciate your info. Sounds like I need to look into things a bit more.

The baffles I purchased are these: http://adoproducts.com/as_provent except they have the pattern of these: http://adoproducts.com/as_durovent-baffle

When I'm putting up the ceiling should I put up a plastic sheet before the ceiling? Or should the spray foam go directly against the ceiling?

 

[Voi]

I appreciate your info. Sounds like I need to look into things a bit more.

The baffles I purchased are these: http://adoproducts.com/as_provent except they have the pattern of these: http://adoproducts.com/as_durovent-baffle

Baffles tend to be expensive although easy to install. It might be worth taking the time to nail up plywood or even rigid foam over the top chords of your trusses.

I would Google [site built baffles] without the brackets or some combination of similar search terms.

When I'm putting up the ceiling should I put up a plastic sheet before the ceiling? Or should the spray foam go directly against the ceiling?

Is the ceiling drywall? I'd want some sort of barrier that would allow me to remove or repair a section of ceiling if necessary.

Installers have different opinions on this so I'd talk to them. When I was deciding how to insulate my un-insulated cabin I got different opinions. I had an interior wall that needed insulation due to needing to heat a mechanical room on the other side. On one side there was already drywall and vapor barrier installed towards the conditioned side.

I considered spray foam and some installers said they could go right over the poly and another said it would need to be cut out. I believe a third said in needed to be cut out but I could put something else up if I was concerned with even needing to repair drywall. He gave me some options as to what could be put up but I don't recall what they were.

As it is I insulated that wall myself with Rockwool.

 

[The One]

Baffles tend to be expensive although easy to install. It might be worth taking the time to nail up plywood or even rigid foam over the top chords of your trusses.

I would Google [site built baffles] without the brackets or some combination of similar search terms.



Is the ceiling drywall? I'd want some sort of barrier that would allow me to remove or repair a section of ceiling if necessary.

Installers have different opinions on this so I'd talk to them. When I was deciding how to insulate my un-insulated cabin I got different opinions. I had an interior wall that needed insulation due to needing to heat a mechanical room on the other side. On one side there was already drywall and vapor barrier installed towards the conditioned side.

I considered spray foam and some installers said they could go right over the poly and another said it would need to be cut out. I believe a third said in needed to be cut out but I could put something else up if I was concerned with even needing to repair drywall. He gave me some options as to what could be put up but I don't recall what they were.

As it is I insulated that wall myself with Rockwool.

I'm using metal roofing material for the ceiling and walls. I can't envision ever damaging them to the point of wanting to replace.

My insulator should be giving me a call later today so I'll run these questions by him too. As it is, I don't always trust the opinions of contractors... At least with my varied past experiences. So I always like to look things up online first.

 

[The One]

Before: make sure your fire insurance policy doesn't prohibit flammable insulation

I asked them today and they do not care what materials are used in the detached structure as long as the insured value matches.

maybe you can add some support framing now for a platform type storage idea that will be used later-sounds easier than digging thru that blown in insulation...

I thought about it but my W trusses and sloped roof don't leave much room for storage. I'm planning on building a purpose built workshop in the future so I'm fine with just having a few sturdy shelves for storage for now.

 

[b4z]

Is your garage heAted? If you have single pane windows spray foam can cause a large amount of condensation on the insides of the windows, because the building is so tight that your heating system is now oversized and doesn’t run enough to remove the moisture in the air. A $4900 spray foam job in my attic cost me almost $9000 in replacement windows and later a used downsized hvac system that I bought from a friend on Facebook, $1500 for that, not including installation.though.

 

[The One]

Is your garage heAted? If you have single pane windows spray foam can cause a large amount of condensation on the insides of the windows, because the building is so tight that your heating system is now oversized and doesn’t run enough to remove the moisture in the air. A $4900 spray foam job in my attic cost me almost $9000 in replacement windows and later a used downsized hvac system that I bought from a friend on Facebook, $1500 for that, not including installation.though.

I haven't installed a heater yet. The HVAC guy is coming out again this week to go over some changes with me in the setup I want and I'm going to go over the actual insulation values I'll be hitting in the walls and ceiling. The furnace he first proposed was a 97% but I didn't get a full spec sheet.

The windows are Andersen 100 double pane low-e. The garage doors are being swapped out for R-18 2" doors. The least insulated part is going to be the concrete.

 

[theoldwizard1]

Should I have him place planking on top of the spray foam before doing he does the blown in?

Not a bad idea to nail down a few 2x6s for crawling around on ! They don't need to be butted together so you should get a true 12" surface. If your a klutz like me, THREE 2x6 would be better.

 

[yeldogt]

I'm confused about the ceiling ... why not do the roof deck and be done with it?

The foam guys are normally good with the proper prepping and they spot the windows with another product -- it's different foam (less expanding/ different color).

The foam has a high flash over point ---- I had a house fire and the foam actually stopped the fire -- it's burned through the studs and the foam was still in place.

There is a video from many years ago trying to scare people -- it's a foamed building (no windows w/ exposed foam. They started a fire in the middle and allowed the fire to burn -- it basically heated the interior to levels above a typical fire temps and where any wood products would have already gone up. Eventually -- the building flashed over .. and they blamed the foam.

If I ever build a conventional home again -- I'm foaming the bedrooms off. I was really impressed at how the foam protected the building --- it does not allow air movement -- so the fire can not cut it's own path.

 

[The One]

I'm confused about the ceiling ... why not do the roof deck and be done with it?

My understanding is that in this type of construction it's better to insulate the ceiling and not the roof? I don't know much about building and am learning as I go so any input you have would be great.

I'm fairly sure that my concrete is uninsulated, as long as the inside temp stays fairly constant will the concrete heat up and be more comfortable to walk and lay on?

 

[yeldogt]

What type of construction. With spray foam (closed) --- I do the whole thing and it done and over with.

You can't really do much about the floor -- it is what it is regardless of the heating or insulation. Having the ability to keep some heat along the floor helps -- it really depends on how cold it's going to get .. how exposed the slab ends or foundation is

 

[The One]

What type of construction. With spray foam (closed) --- I do the whole thing and it done and over with.

You can't really do much about the floor -- it is what it is regardless of the heating or insulation. Having the ability to keep some heat along the floor helps -- it really depends on how cold it's going to get .. how exposed the slab ends or foundation is

It looks like this:

https://www.constructiontuts.com/wp-content/uploads/2018/05/Basic-Components-of-a-Roof-Truss.jpg