Retrofit insulation?

[Jaguar Fan]

In a separate thread I started, several of you suggested both high R values and construction techniques.

Here is a related but separate question:

I'm looking at buying a 2 year old house (already finished & lived in) but its insulation are not up to the standards I would expect. It uses traditional fiberglas batting to acheive R19 in the walls and R30 in the ceiling.

At one extreme, I suppose I could remove the sheetrock from the interior perimeter walls & reinsulate & re-scheetrock & re-paint. That would be a big project.

Do I have any alternative to that for the perimeter walls if I want to increase insulation? (aside from just ignoring the house)?

I assume that for the ceiling I could just blow in additional insulation on top of the existing batts (or remove & reinsulate).

It is in Las Vegas area -- it gets down to about 20 degrees F in the winter but up to 115 to 120 F in the summer.

 

[hick]

Living in Vegas i can tell you that the northern method of applying foam to the outside of the home when putting new siding on won't work, as that would be the first thing i would have suggested.

Other then that, i am currently in the same boat as you. I live with my old man and in the process of running some cable in the attic we took notice of the very... seemingly lacking... blown in insulation... which had led us to wonder about the exterior walls as well...

 

[krooser]

Most heat loss occurs thru the roof... add some extra batting in the attic.... leave the walls alone cuz you'd soend way more than you'd ever save on fuel.

 

[Fins/413]

Most of your heat loss/gain will be through the ceiling, more batting or put blown in cellulose right over the existing batting. If the windows aren't up to snuf you could consider some new high tech windows. Also awnings if there isn't a adequate shade on the windows on the sunny sides of the house. Being in such a sunny location things like solar collectors might be cost effective over a reasonable period of time depending on your situation.

 

[rsanter]

for an exsisting home I would not rip out the walls to redo anything. I would look to seal your air leaks by blowing foam in and around all of you electrical boxes and pipes that are on a perimiter wall. I would also load up the ceiling with more insulation.
I would also go in and really seal up all of your AC ducting and foam around where the AC vents mount into the walls.
you can also add insulation around your AC ducting in the attic.
look at all your windows and doors and do the best to seal those up and any windows that get direct sun should be replaced with the dual pane E2 windows.
you can also shade you AC condensor a bit if it gets direct sun

start with that and you will see an improvement without spending tons of money

bob

 

[Jaguar Fan]

Thanks for the suggestions!

 

[brad d]

Living in Vegas i can tell you that the northern method of applying foam to the outside of the home when putting new siding on won't work, as that would be the first thing i would have suggested.

why would that not work?? could you not just install 1-1/2" of foam then paper and mesh.. then stucco over that?

I have seen it done up here.

 

[hick]

why would that not work?? could you not just install 1-1/2" of foam then paper and mesh.. then stucco over that?

I have seen it done up here.

Two VERY different construation methods of the homes here.

Up North where you are (i am originally from Edmonton as well) the homes have siding or stucco in the older homes with some sort of plywood underneath it which is easy to get to when attachting foam ontop with the intention of putting more siding on top. Also the stucco used it different the stuff here and deals with holes being put threw it to reach what ever is behind it

Its difficult to explain, but homes here use a stuco/plaster EVERY WHERE on the exterior. Bullnozed corners EVERY where... the window sill, corner of the houses, door frames... make its VERY difficult, impossible i would say, to attach foam board to it and then some thing else on top of it

I will see if my digital wants to work and snap some pictures so show you what i mean

 

[Gary S]

If you already have R19 in the walls in a mild climate like that, you are wasting time and money trying to increase the wall insulation. Your windows are probably R2. Put your time and work there if you want improvement.

 

[Jaguar Fan]

If you already have R19 in the walls in a mild climate like that...

Hi Gary,

"mild climate"? In Las Vegas, NV? In the middle of the desert? Yes, the winter only gets down to 20 degrees F and I suspect that's what you are referring to when you say "mild" (at least relative to North Dakota). It is the summers I'm worried about -- Daytime temps of 120 in the shade but there is no shade. At night in the summer, it cools down to maybe 100 but maybe not.

So I am more concerned about the heat gain in the summer.

I'm looking at putting in shades to help with the windows -- something like this: http://polarshade.com/ to help reduce heat gain.

 

[Bermudacat]

In a separate thread I started, several of you suggested both high R values and construction techniques.

Here is a related but separate question:

I'm looking at buying a 2 year old house (already finished & lived in) but its insulation are not up to the standards I would expect. It uses traditional fiberglas batting to acheive R19 in the walls and R30 in the ceiling.

At one extreme, I suppose I could remove the sheetrock from the interior perimeter walls & reinsulate & re-scheetrock & re-paint. That would be a big project.

Do I have any alternative to that for the perimeter walls if I want to increase insulation? (aside from just ignoring the house)?

I assume that for the ceiling I could just blow in additional insulation on top of the existing batts (or remove & reinsulate).

It is in Las Vegas area -- it gets down to about 20 degrees F in the winter but up to 115 to 120 F in the summer.

Not sure messing with the walls would help. Check this out;

The effectiveness of an insulated ceiling, wall or floor depends on how and where the insulation is installed.

Insulation which is compressed will not give you its full rated R-value. This can happen if you add denser insulation on top of lighter insulation in an attic. It also happens if you place batts rated for one thickness into a thinner cavity, such as placing R-19 insulation rated for 6 1/4 inches into a 5 1/2 inch wall cavity.
Insulation placed between joists, rafters, and studs does not retard heat flow through those joists or studs. This heat flow is called thermal bridging. So, the overall R-value of a wall or ceiling will be somewhat different from the R-value of the insulation itself. That is why it is important that attic insulation cover the tops of the joists and that is also why we often recommend the use of insulative sheathing on walls. The short-circuiting through metal framing is much greater than that through wood-framed walls; sometimes the insulated metal wall's overall R-value can be as low as half the insulation's R-value.

http://www.ornl.gov/sci/roofs+walls/insulation/ins_02.html



For the attic, blowing insulation in is a quick, easy half day job. Make sure to install baffles to keep your soffet vents clear. The guys who will sell you the blow in insulation will be a great resource for information.

 

[307WYLD]

Hi Gary,

"mild climate"? In Las Vegas, NV? In the middle of the desert? Yes, the winter only gets down to 20 degrees F and I suspect that's what you are referring to when you say "mild" (at least relative to North Dakota). It is the summers I'm worried about -- Daytime temps of 120 in the shade but there is no shade. At night in the summer, it cools down to maybe 100 but maybe not.

So I am more concerned about the heat gain in the summer.

I'm looking at putting in shades to help with the windows -- something like this: http://polarshade.com/ to help reduce heat gain.

What is wrong with the window film they have available for putting on the interior house windows? Very effective and depending on what brand you buy it doesn't have to look like hastily done WalMart car window film.