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-   -   Insulating the crawl spaces and basement with Batt insulation (http://www.houserepairtalk.com/f106/insulating-crawl-spaces-basement-batt-insulation-17610/)

drewdin 04-28-2014 10:17 AM

Insulating the crawl spaces and basement with Batt insulation
 
I am going to be Insulating the crawl spaces and basement with Batt insulation, my question is that since I'm using batt insulation how can I prevent it from falling down or getting insulation on everything over time?

Should i put 1/4 blue foam board under it or do something similar? If you want pics let me know but i don't have insulation up yet.

Thanks

nealtw 04-28-2014 10:39 AM

No, the floor sheeting is a vapour barrier so you want free air flow below the insulation, cut 1 1/2" slats out of 1/4" plywood or if you might have critters you might put up a wire mesh.

beachguy005 04-28-2014 03:46 PM

A house I used to own had a 3 foot crawl space that was 24'x40' and when they did the insulation they stapled string in a criss cross pattern. A lot of work.

Now you can buy pre-cut pieces of wire that are made for you slide up between the joists to hold it in place, or use wood strapping which is cheap.
http://www.homedepot.com/p/Simpson-Strong-Tie-16-in-OC-Insulation-Supports-100-Pack-IS16-R100/100375163

I've also seen where people have added tyvek stapled to the underside of the joists.


The foam board may need to be covered for fire rating.

drewdin 04-29-2014 11:15 AM

1 Attachment(s)
Hi Guys,

My goal is to insulate the crawl spaces and my basement for sound and temperature. That is why i was thinking about putting the blue foam board over the insulation after its up, but i don't want to make something else bad by making the floor sound proof.

So I should not use the blue foam board and just put the insulation in the rafters?

I am just worried that little pieces of insulation would fall over time so I wanted to cover it with something if possible.

The previous owner put blue foam board on the rafters and i removed it, Here is a pic of one of the offending areas i want to insulate. I already put 6mil poly covering the walls and floor.

Thanks

nealtw 04-29-2014 11:59 AM

Part of the problem you are seeing with insulation falling out in bits, is the fact that he installed bits and peices.
Some of the mistakes people make, is not reading the instructions.
Often you find that the small areas people just stuff in scraps. They should be carefully cut 1" to wide for the space
Joists that are 16" on center have a gap of 141/2 and the insulation for that are a little bigger, but if you measure those gaps, they can be all over the place and there should be a bag of wider insulation for fitting the wider gaps. If done right you will have very little fall out.

beachguy005 04-29-2014 06:42 PM

Typically the blue board is covered with siding but I don't know if it has to be covered. One side of it is covered with aluminum which should face the heated space, or up in your case.
But given that you're installing insulation, of what R value I don't know, adding more rigid insulation may not have any value.
You don't typically lose a lot of heat through the floor. There's probably no sound reducing value to the rigid foam and given it's a crawl space is noise even a real issue?

drewdin 04-30-2014 10:54 AM

I have removed all insulation from the crawl space, no pink or blue foam board. I plan on doing it right and wanted to see what the best way is. The sound is only an issue as my boiler is very loud, i can hear it kick on when I'm in the room above and it resonates. I plan on at the very least insulating the floor joists, the blue foam was an overkill attempt at sound dampening, unless the effects are useless.

nealtw 04-30-2014 11:15 AM

Perhaps you could build a cover for the boiler. Might have code requirments

drewdin 05-01-2014 11:05 AM

Quote:

Originally Posted by nealtw (Post 104229)
Perhaps you could build a cover for the boiler. Might have code requirments


Didn't pass the wife's code requirements....

Perry525 05-23-2014 11:29 AM

Insulating crawl space? Why?
 
Quote:

Originally Posted by drewdin (Post 104107)
I am going to be Insulating the crawl spaces and basement with Batt insulation, my question is that since I'm using batt insulation how can I prevent it from falling down or getting insulation on everything over time?

Should i put 1/4 blue foam board under it or do something similar? If you want pics let me know but i don't have insulation up yet.

Thanks

The first Law of Thermodynamics is: heat always moves from hot to cold.

I assume that you really want to keep the heat inside your living space?

Presumably the crawl space is cold and not used for living?

So the heat moves from your living space, into the floor by radiation and conduction then into the joists and then the cold air inside the crawl space, the crawl space walls and floor.

To get the best result, keep the heat in your living space, the insulation must be above the floor. That means sheets of closed cell insulation, like polystyrene, laid on the existing floor with a fully floating floor on top.

Placing insulation below the floor, is an almost complete waste of money and time, as wood is not a good insulation, and your expensive heat is quickly passed into the joists, cold outside air, crawl space walls and ground.


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