Home>Discussions>INSULATION & HVAC>Replace Fiberglass Insulation with Foam
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Re: Replace Fiberglass Insulation with Foam

North Carolina is in Zone's 3 4 & 5
according to the IRC (international residential code 2006) recommended r-value is 30 for Zone 3 and r-38 for zone 4 & 5 so the r-20 isn't enough insulation

tiger foam is more for small projects, you want to have a professional for this job

canuk
Re: Replace Fiberglass Insulation with Foam
Earnie wrote:

The flat ceiling will be easy and the one being looked at today. The other half of the ceiling is sloped and consists of 2x12's with kraft faced batting between them. T&G boards on the inside/ceiling and roof decking on top (I hope there is a gap for venting). I am almost positive that it will be impossible to remove the batting and spray foam in the cavity.

The roof will need replacing in the future. My thought is to have the roof decking removed. pull out the batting, then spray foam to the ceiling T&G boards. Again this would seal the T&G board gaps.

Earnie ....perhaps I'm missing something here.

You mention removing the roof sheathing and applying whichever insulation from the top side.

To my thinking this is an expensive way of simply adding insulation to an attic space. The other thing that would concern me would be having the roof open to the elements.

You would have to have incredible timing and cooperation between the roofers , the insulation contractor and of course mother nature. The roofing would be removed completely then the insulation applied immediately with the new roof being applied immediately after the insulation is installed.

Not that it can't be done but there will be a lot of people on that roof and with it opened hopefully the weather doesn't rain.

In my thinking it would be more logical to do the insulation from the inside.
Considering there are 2x12 rafters provides plenty of options for achieving adequate insulation.

Baffles can be installed to the underside of the roof sheathing which will provide the air space. The baffles can be either ones purchased or made from 2x2 nailers on the rafters with foam sheets or plywood attached to the nailers.
Insulation can then installed from the baffles to as deep as you wish ... regardless of bat or spray foam.

This can be done without concern to what the weather is outside.

The thing that will prevent you from DIY is the reluctance of removing the T&G in the attic.

Just my 2 cents:)

btw .... for the record ... I hate and don't use duck ( aka duct ) tape.:D

JLMCDANIEL
Re: Replace Fiberglass Insulation with Foam
canuk wrote:

The thing that will prevent you from DIY is the reluctance of removing the T&G in the attic.

Just my 2 cents:)

Read it again Canuk. The T&G is o his ceiling below the attic, but he hasa open cracks and is afraid yhat the foam will come through to the room below.
Jack

canuk
Re: Replace Fiberglass Insulation with Foam
Quote:

T&G boards on the inside/ceiling and roof decking on top (I hope there is a gap for venting).

Perhaps I'm misinterpreting what is meant by this. I was thinking the ceiling of the attic is also covered by T&G. If that's not the case then this should be easier to do from the inside.

I do recall the floor/ceiling of the bedroom being T&G.

JLMCDANIEL
Re: Replace Fiberglass Insulation with Foam

Canuk,
And it didn't take a 300 word dissertation to explain it.:D
Jack

canuk
Re: Replace Fiberglass Insulation with Foam
JLMCDANIEL wrote:

Canuk,
And it didn't take a 300 word dissertation to explain it.:D
Jack

What are you saying ??:D :p

Earnie
Re: Replace Fiberglass Insulation with Foam

Guys, my point is this.

We live in this house. The T&G ceiling boards are pine wood, stained and sealed. Yes, some do show signs of not being completely tight together, hence the thought that we are loosing conditioned air up through the gaps into the attic.

To re-insulate a sloped ceiling from the inside requires ripping down lots of T&G boards inside the house. Not to mention the dust, dirt, fiberglass insulation that will be falling into the house.

To me, it makes more sense to remove the roof decking, then the fibeglass insulation between the rafters, and then install spray foam thereby sealing the T&G gaps. When we re-roof, its just one more (expensive) step to remove the roof decking, then replace it.

Time sensitive, you bet. Expensive, very. I wasn't the one who constructed this, nor was I the inspector who allowed this to pass who knows what county or state energy efficiency codes. I just have to deal with it.

Thanks for the valued input. Please keep posting if you have any other thoughts. I have gleaned much from you replies.

canuk
Re: Replace Fiberglass Insulation with Foam

Earnie .... gotcha.:)

JLMCDANIEL
Re: Replace Fiberglass Insulation with Foam

Earnie,
I have a story and a half also so I know what you're talking about. I think you have the right idea for handling the slanted part of the ceiling. It will be a pain and I wish you all the luck.:)
Jack

Earnie
Re: Replace Fiberglass Insulation with Foam

A bit if a follow-up.

Spoke to another contractor who uses Demilac products.

http://www.sealection500.com/dem/s500/index.php

Anyone use this or heard of this product?

One plan is to remove the old fiberglass batts, spray about one inch of closed-cell foam for the air barrier, then re-install the batts.

Since the existing batts are kraft faced, would there be an issue with re-installing the old kraft batts on top of the foam? Or should non-kraft batts be used?

If new non-kraft batts are necessary, would blown-in insulation be better on top of the foam?

Thanks!

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