# Idea for insulating between floors.... good/bad...?



## Tom Struble (Dec 29, 2008)

your probably better off insulating the basement walls
for thermal value


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## angus242 (May 1, 2008)

I think you'd be better off to attack the joist bays from below. Much easier to repair drywall. I don't like the idea of drilling holes in the subfloor. The deflection (bounce) of your main floor is directly related to the strength of your subfloor.


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## AtlanticWBConst. (May 12, 2006)

angus242 said:


> I think you'd be better off to attack the joist bays from below. Much easier to repair drywall. I don't like the idea of drilling holes in the subfloor...


I agree, not to mention having to disrupt the finished floor.

One thing to take into consideration is if you have recessed lighting. If the units are not I.C. rated (for insulation), then you will have to work around that issue, or replace them.


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## Termite (Apr 13, 2008)

I definately agree that going at this from the top side isn't a great way to do it. You'd definately be better off repairing a couple strips of sheetrock the length of the basement than you would be drilling holes in the subfloor.


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## Garasaki (Apr 14, 2008)

Keep in mind the holes you are drilling will need to be big enough to accomidate the insulation blower (probably 3") plus some room to wiggle the nozzle around to direct the insulation (maybe an additional 3"?). So now your drilling 6" holes in your subfloor  probably not a good idea.

Plus you'll need a lot of em to insure complete coverage of the insulation.

Also keep in mind the subfloor itself is part of the noise reducing assembly. So now your cutting a bunch of holes for noise to travel thru, in order to reduce the amount of noise that travels thru...

I agree that cutting holes in the subfloor is probably not the most effective approach.


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## markus (Jan 4, 2009)

Not to mention that turning your floor into swiss cheese is not a very good idea from a structural perspective. Your subfloor keeps your floor joists nice and tight. If you have wires in there those will be hard to navigate with a hose regardless if you have potlights.

Pull the drywall in the basement, it's so much easier to do from below. It's more man hours, and will be a lot of work but you'll have a much better result doing it that way. Plus, once you got the drywall off, if you got the ceiling height, you can consider using resbar (metal strips that separate the drywall from the joists) to further eliminate sound travel. Don't forget to use the green Roxul "safeNsound" insulation. Blown insulation has nothing on that stuff!!!


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## Ininkus (Dec 28, 2008)

Alright guys, I'll heed to your advice. It's just so dang tempting when you have all the carpet out and the subfloor is staring at you saying "Now is the time to do something!!!" But, all valid points posted.

I am horrible at drywall, the cieling is textured, and I hate painting more than anything in the world... so before I do anything below I will do nothing at all, haha. :yes:

I guess before the hardwood goes down I could look into thermal sub floors or heat... but ick.. more money!

Thanks!


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## Garasaki (Apr 14, 2008)

You could maybe look into "quiet" subfloor systems, although those tend to be designed to keep the sound of footsteps from travelling between floors rather then typical voices and what not. But it may be a way to provide some sound attenuation without tearing up the drywall.

Be forewarned, I am not knowledgable on those floor systems at all... :huh:


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## markus (Jan 4, 2009)

Ininkus said:


> I am horrible at drywall, the cieling is textured, and I hate painting more than anything in the world... so before I do anything below I will do nothing at all, haha. :yes:


Being a drywall pro, textured ceilings are actually way easier than smooth ceilings and require a lot less work! 1-2 less coats required, and no final sanding! You could also look to rent a spraygun and then trowel over it, or just spray gun it. You have a lot of choices with textured ceiling, you can always change it up.

Good luck!


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## 4just1don (Jun 13, 2008)

they blow sidewlls here all the time,,,whats the differnce between a side wall and a floor. They drill a 1 inch hole for blowing thru(aproximetely) maybe 1 1/4 at largest. mennards gives you the blower if you buy product there,,,check with them for hole size,,that size hole in drywall in basement isnt hard to fix,,,they may even make a pop in plug till next time your ready to paint!!

personnally I LIKE the idea!! Nothing like avoiding heating cubic feet you dont need to,,plus the sound deadening,,,cool


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## markus (Jan 4, 2009)

4just1don said:


> they blow sidewlls here all the time,,,whats the differnce between a side wall and a floor. They drill a 1 inch hole for blowing thru(aproximetely) maybe 1 1/4 at largest. mennards gives you the blower if you buy product there,,,check with them for hole size,,that size hole in drywall in basement isnt hard to fix,,,they may even make a pop in plug till next time your ready to paint!!


That's true, the only difference is there's no feet or heavy objects sitting directly over those sidewall holes. I recently had sidewalls blown in but they still put a wood plug to "maintain integrity" as they put it. I can imagine over time if I was stepping on it, it might become loose and squeak over time.

Holes in the ceiling can be patched using the plastic bag trick for textured ceilings..


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## Ininkus (Dec 28, 2008)

Ut oh... now the idea is back in my head. 

Ya know, I understand the swiss cheese concern, but think of this; I'm going to be putting tile down, which will require that cement board to be screwed down (whatever that stuff is called). Won't that be PLENTY of reinforcement over my swiss cheese floor.....?


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## markus (Jan 4, 2009)

Ininkus said:


> Ut oh... now the idea is back in my head.
> 
> Ya know, I understand the swiss cheese concern, but think of this; I'm going to be putting tile down, which will require that cement board to be screwed down (whatever that stuff is called). Won't that be PLENTY of reinforcement over my swiss cheese floor.....?


Possibly.. but the idea scares me. I'd hate to say yes and then your tile cracks because of the bounce in the floor as a result of a hole(s)...


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## angus242 (May 1, 2008)

Ininkus said:


> I'm going to be putting tile down, which will require that cement board to be screwed down (whatever that stuff is called). Won't that be PLENTY of reinforcement over my swiss cheese floor.....?


Absolutely not. *Cement backer board offers NO structural support whatsoever.* 
Again, I HIGHLY recommend AGAINST drilling any holes in the subfloor.


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## Ininkus (Dec 28, 2008)

Thanks to all that posted... Yeah, I've decided to skip it. 

Angus242, wow, you do really nice work. Saw the pics of the kitchen re-do's.


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## tmpyankee (Aug 25, 2008)

Ininkus said:


> I guess before the hardwood goes down I could look into thermal sub floors or heat... but ick.. more money!
> 
> Thanks!


If you want radiant heat in your floors (great idea by the way--I have it and LOVE it!!!!), the best way to do it in an existing structure is from the floor joists below (i.e., tearing out the drywall in the floor below). There are really great products that get installed under the existing subfloor, between the joists. If ever there is a problem with the heating system, you can always attack it from the ceiling again. However, those mat-style systems that you lay on top of subflooring limit the types of flooring you can use and cannot be repaired without removing the flooring again. It's unlikely you'd need to make repairs, but something to consider nonetheless.

PLEASE!!! Do not put holes in your subfloor. The previous comments about structural integrity are completely accurate. It is so much easier to pull out the drywall (do this yourself) and then hire a drywall contractor to reinstall it. The most I have ever paid for drywall was $17 per sheet to have it installed, taped, mudded and finished to be ready for paint (and you can paint it yourself). In the meantime, you can easily install batt insulation yourself. It's a dirty job, but in the end it is the better route. (As a side note, it would also afford you a great opportunity to install can lights. It's very easy to do at that stage, and they look fantastic!!!).

Just because you're putting down cement board doesn't mean you can compromise your existing subfloor. You have to have a sound subfloor before you would want to install cement board for a tile installation--they go hand in hand.

Also, I have to recommend that you try to avoid textured ceilings if at all possible. I flip houses for a living, so I deal with buyers and realtors a lot. Trust me--buyers hate textured ceilings. It really dates a property. Something to consider for possible future resale.

OK, that's my 2 cents. 'nuff said.


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## Ininkus (Dec 28, 2008)

Thanks for all your feedback and advice Tmpyankee.

Definately not going to swiss cheese my floor after all the replies!

What type of radiant heat do you prefer working with? Are there any that you have found to be efficient and economical at the same time?

Best regards!


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## Baron (Jan 6, 2009)

I have never drilled holes very large for blown insulation into walls or ceilings, usually around 1 1/2", but I have seen hot air ducts of some rather large sizes in as many as six locations in a room with no inspector or builder concern about the structural integrity of the sub floor being weakened and causing harm. So I am not sure if that is a major concern if the holes are small.

Personally I would go through the drywall as I find that easier to patch. However I would be more concerned about trapping cellar dampness if that was an issue at your location that would cause mildew build up in the ceiling over time.
I would be sure to check for the moisture levels in the basement before considering the ceiling insulation and perimeter insulation would be more my concern than cool floors.


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