Insulation help / input needed.

[Capt Chrysler]

Hello Folks,

I need your input on this.

We need to replace the house siding next spring. At this time I would like to reinsulate the house.

So do we blow more into the wall cavity?

Open cell foam it?

Strip the sheeting, remove the old insulation & go back with fiberglass.

Thanks

Capt. Chrysler

 

[wildstyle]

How about rigid foam on the outside under your new siding?

 

[carrerakid]

If there is already fiber glass or rockwool in the wall blowing in anything will not work well. Removing it all is very time consuming and expensive. Your best bet may be to foam around Windows and doors and properly install a quality house wrap to minimize air infiltration. If there is no insulation in the walls blow cellulose in addition to the above measures.

 

[matt_i]

It only makes sense to me if you currently have *no* insulation in the walls. Unsheathing the house from the outside is going to be megabucks or megatime or both. Stuffing more in there (iow adding to existing) does no good.

 

[Capt Chrysler]

Thanks Folks,

We are replacing the windows also at this time. The fiberglass that's in the now looks to be about 1.5 inches thick as the house was built in 1954.

I think we need to remove the current fiberglass and start over. It might cost more, but will it be better in the long run?

Anyone have any input on Blow Cellulose in a wall cavity?

Thanks

Capt. Chrysler

 

[sco44]

If u have existing insulation you can do injection foam (non expanding). Look at cfi foam to understand the concept. That's the best option with existing insulation and not taking off sheathing.

You could also leave sheathing and existing insulation and add 1-2" ridged foam on exterior.
This requires new custom trim out, but you said u are already doing new windows. Will also have doors, exterior electrical boxes to fir out and misc other things

The benefit of ridgid foam outside the sheathing is a thermal break in your walls.

Whats your climate like? Are the walls 2x4 or 2x6?

-Scott

 

[Capt Chrysler]

If u have existing insulation you can do injection foam (non expanding). Look at cfi foam to understand the concept. That's the best option with existing insulation and not taking off sheathing.

You could also leave sheathing and existing insulation and add 1-2" ridged foam on exterior.
This requires new custom trim out, but you said u are already doing new windows. Will also have doors, exterior electrical boxes to fir out and misc other things

The benefit of ridgid foam outside the sheathing is a thermal break in your walls.

Whats your climate like? Are the walls 2x4 or 2x6?



-Scott

2 X 4, Nebraska, Hot in the summer & cold & windy in the winter.

 

[volaredon]

Tips on insulation? it ***** to deal with....

 

[sco44]

With 2x4 walls and already planning to replace the siding/Windows, I would go 2" ridgid foam outside of existing sheathing. Gonna be a better performing system. I'm assuming that 2" of existing is rockwool. Might get around r15-18 with that setup, plus the benefits of a thermal break.

-Scott

 

[boobag]

With 2x4 walls and already planning to replace the siding/Windows, I would go 2" ridgid foam outside of existing sheathing. Gonna be a better performing system. I'm assuming that 2" of existing is rockwool. Might get around r15-18 with that setup, plus the benefits of a thermal break.

-Scott

thats a lot of foam. you'll have to build up ever window and door trim, plus how do you nail your siding on? with 3" nails? lol
the siding will also stick out past the foundation a lot.

 

[Kaizen]

I think I'd do a test with blown in. do you have a wall you can try a few bays on? in an 8 foot tall x16 inch cavity you would drill two holes. about 3 and 6 feet. then you put up a snake to make sure you don't have any fire blocking. if you do like between a 1st and second floor you have to account for that. my house had cotton blown in probably in the 80s. when I redo rooms and pull the exterior walls its still packed in with maybe an inch or two of settling.
if you're using vinyl siding I'd also use tyvek house wrap AND tape every seam, 1/2 inch accordion insulation panels, and non expanding foam on every window and crack. get new construction windows with an exterior flange you can nail to the house not replacement windows. if the blown in doesn't work not sure. foam injection isn't cost effective in my eyes. it would be cheaper to rip out the drywall yourself and put in good insulation.

 

[sco44]

Foam on exterior isn't the cheapest/easiest for sure. It's probably the highest performing though. And believe it or not it's a common practice. And it would probably be screwed lol. Not sure why sticking past the stem 1.5-2" more would be an issue.

It didn't sound to me like ripping all his drywall out was an option. Either way, there's quite a few options

-Scott

 

[sco44]

I got a quote for injection foam. 1800sqf, 2x4 construction, single story rambler. 6k, I thought that was reasonable.

 

[homebuilt burner]

When I put new windows in my house I built them out 1" form the existing wall. The the next year pulled all the old siding off installing 1" of styro and sided over the top. It helped. Yes you will have to reframe windows and doors. I looked at blowing cellulose into the walls and talked to a couple of people I know that had so. The general consensus was that the gain was not really worth the expense and most said they would npt do it again, and would pursue other options.

My next step is to gut the whole house and spray foam from the inside.

 

[Capt Chrysler]

I looked at the pump in foam. Just didnt get a warm and fuzzy feeling from the installer. I even looked at a spray foam rig with an HVAC friend a couple of years ago.

Gutting the inside is not an option as it doesn't need replaced. One contractor wanted to add shims to make the walls 2x6 then use batt insulation. OSB the "new" wall, Tyvex and side.

I like cars, machines and steel stuff. This wood stuff has me really messed up.

Capt. Chrysler

 

[bandaidmd]

Keep checking with spray foam installers theres a process they do to add foam to existing insulation.

 

[Voi]

We are replacing the windows also at this time.

I would absolutely price a layer of exterior foam since you're doing windows at the same time. I have a PDF that discusses this practice but can't seem to find it at the moment. If can't imagine tearing off current sheathing unless it's in bad shape.

 

[jives]

You should do an extensive search of the Building Science website, e.g.,

http://buildingscience.com/document...ulation-finish-systems-eifs-wall-construction

and the Green Building Advisor website.

http://www.greenbuildingadvisor.com/blogs

 

[Voi]

Couldn't find the PDF I was thinking of but here is a link to another one I've read. It's more about new construction than retrofit but I'll post it anyways.

http://www.finehomebuilding.com/design/articles/a-better-wall-with-exterior-foam.aspx

I agree with Jives - search the two sites he listed. A lot of good discussion.

 

[Capt Chrysler]

Thanks

Capt. Chrysler

 

[engineer2]

Anyone have any input on Blow Cellulose in a wall cavity?

I have that and it insulates well but wind goes right through it unless you have Tyvek on the outside. The biggest issue is mice love it as nesting material and will chew through the outside sheathing to get to it. They make nests and tunnels inside the walls and you can hear them at night. If you use it, you have to make the exterior sheathing rodent proof.

The hot ticket these days is spray foam, but you need to suit up for it since it has isocyanates or hire someone to do it.