DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (
-   Insulation (
-   -   DIY Attic insulation retrofit (

Lin in NY 08-07-2011 09:30 AM

DIY Attic insulation retrofit
I have had several contractors give estimates and tell me stories about my house I know to be untrue. I may be a 60 year old widow, and look vulnerable, but I worked for quite a few years in theater construction (professionally), so i know my way around a few tools and ladders.
Here is the problem: House built @ 1910 in NY state; re-roofed, with a center vent the length of the attic. No soffit vents - would be real inconveniet to do it now. It had @ 3" of poured cellulose between the joists placed @ 1950 (we guess). Then a contractor laid 4" of (yellow) fiberglass, barrier down, on top of it (1978). Then the guys who did the roof (1994) put 1/2" loose plywood on top of the fiberglass in many areas for catwalks, compressing it, and left it there. I want to add insulation, and perhaps an additional vapor barrier. I don't want to remove everything and start from nothing. I'm not trusting anyone who has come in for estimates - they've all lied to me about what's up there because they think I haven't looked.
Have you a suggestion on what I should do?

I would be so appreciative.



Jackofall1 08-07-2011 09:39 AM

Welcome Lin in NY, to the best darn DIY'r site on the web.

Sounds like you have a managerie of insulation in your attic.

Well you have identified something that should be high on your list is soffit vents.

Secondly, vapor barrier needs to be on the warm side of the sandwich, so in order to add VB, you would need to remove or displace temporarily the existing insulation to get the VB down to where it needs to be.

Remove the plywood pieces.

Then blow-in or have blown in 16-20" of cellulous.

Good luck on your project.


ccarlisle 08-07-2011 10:25 AM

I think someone should have told you that what you want to do ("add insulation") is only part of what you should really be doing up there - which I presume is making your home more comfortable to live

If that's the case, then you should understand that pushing the attic to the outside of the 'house envelope' will involve making the attic "cold"; right now you are somewhere in between the two extremes: having the attic part of the house envelope (ie, "warm) - and having a 'cold' attic - complete with proper air vents and a vapour barrier - and air-sealed.

So, you many easily get a variety of opinions on what needs doing, from just adding insulation, to a complete air-barrier, plus soffit ventilation, plus vapour barrier plus taking everything out - and everything in-between. Depends on the contractors understanding of your whole home.

Ideally - and only if money were no object - you would have to accompany your attic from the 1910's to the 2010's by transforming it from a warm zone to a cold zone. That involves creating an airflow from the soffits to the top vent, removing the existing insulation, putting down a vapour barrier and air sealing the various penetrations, then putting down sufficient insulation for your climate.

That's about the basics of doing that; now how that impacts on your energy bill will depend on how much you do and what else needs seeing to in your home.

But just doing one thing (ie. 'adding insulation' or 'venting the soffits') by themselves won't have much of an impact on your energy bill so long as the other elements aren't seen to. Unfortunately, doing all of them might involve some cash. But that amount of cash would have to be seen compared to other may turn out that doing nothing is one option worth considering. After all, your house was built almost 100 years ago, when times were indeed different.

Most people often overlook the negative effects of improper air-sealing can have on the comfort you enjoy living there. After all, energy audits concentrate on that element - so it's for anyone to wonder why. So don't overlook someone who comes in and quotes on just air-sealing the whole attic...he may be onto something.

Lin in NY 08-07-2011 05:26 PM

Thanks, Gentlemen. ~You have convinced me to do it right, otherwise, what's the point.
There are still a few foreseeable wrinkles: This is a Queen Anne Victorian with an 18" overhang. I plan on disposing of the 4" fiberglass, and most of the loose fill between the joists, but getting that stuff out from the overhand pocket will be nearly impossible. Luckily it has been there for 50 years, and no condensation yet.
So here is the plan:

1. Remove all the old insulation I can reach.
2. Cover/seal all the lighting fixtures, holes for conduit, the chimney, etc.
3 Install some vent baffles so the air can circulate from the overhang to the roof vent. (How many do you think?)
4. Lay R-38 fiberglass batts, paper side down, between the joists. If I wanted to, I suppose I could also add another layer of batting (unfaced) perpendicular to the first course, and increase the R rating to -60 or so.
5. I'd like to also add a radiant barrier on top, but I don't see how to do that without crushing the fiberglass batts I just laid. Do you do it together? There won't be any more catwalks as the joists are only @ 3" deep up there.
6. Do I in some way fasten the battings to each other? Seems like all that wood would encourage seeping heat.

Does that sound all right to you guys?

Thanks in advance.
(BTW, I'm an expert in health insurance if you want to ask me anything (and no - I'm not a broker. I won't try and sell you a policy! We could talk off site.)

Thanks again

Lin in NY

ccarlisle 08-08-2011 06:32 AM

I'm glad you've decided to do it right - to my mind, there's really no other way, with some exceptions of course.

Still, I have a number of misgivings about your situation seeing that Queen Anne's are notorious for having nooks and crannies that are inaccessible to renovation experts, and many resist being brought up-to-date in matters of insulation etc and do so quite unwilllingly. It was the style back then to make things much more intricate that they do since - but that is part of their charm. So please don't underestimate the scope of this job - neither in terms of time, money or effort that it will take to achieve anything like what you hope to achieve in savings - and don't overestimate the combined effects of all this on your energy bills. These houses have a way of undoing a lot of the good people try to do to them.

You will have to put vents into your soffits; exactly how many and where will depend on your exact configuration but several vents will probably be needed every few feet to get the kind of ventilation you need. Each vent will require baffles on the underside of theroof sheathing to provide a channel for air to reach the ridge vent(s). The size and number of the ridge vents will have to be balanced with these soffit vents, so that might need seeing to first.

Once the ventilation has been taken care of, you'll need to air-seal. This isn't a complex job but needs attention to detail and the use of the right materials to be effective. Especialy around chimneys and lighting fixtures. For example, sometimes foam boxes are needed around light fixtures. This is a major step; because air leakage accounts for something lie 40%+ of the heat loss of your attic, so by concentrating your efforts here, you'll get a pretty good bang-for-the-buck.

Then you'll have to look to vapour movement - and the effective placement of a vapour barrier. Almost by definition, a tar-paper vapour barrier on fiberglass batts will be discontinuous - but there are different ways of handling that. Use plenty of foam and acoustical sealants is all I can say here...

Then insulate to your hearts content; I wouldn't neccessarily reach for a radiant barrier over the two layers of fibreglass batts for a number of reasons, so invest the money elsewhere. I am not sure what you mean by attaching the batts together but no, there is no ned for that as long as the batts are firmly and snuggly touching each other i.e. no voids should remain once laid down.

Do you qualify for an energy audit where you are? Might be an interesting way of getting the definite answers to your situation...

All times are GMT -5. The time now is 04:38 AM.

vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

Search Engine Friendly URLs by vBSEO 3.6.1