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Old 11-05-2008, 12:42 PM   #1
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DIY Blown in insulation?


Not sure if thisis the right sub-forum... but. We have a 1947 house with no known insulation. In drilling a hole through the wall, I found the siding, some foil looking stuff, carboard looking stuff, some wood siding looking stuff??? and more cardboard looking stuff. That's it.

We have one room in particular that is very cold which has 3 outside exposed walls, and 2 large windows. I am thinking about doing this but trying to figure out costs, etc., and if it is a feasible DIY job.

My understanding is that for each wall space in between each stud I'll have to drill 2 holes since there is a brace that goes horizontally.

Is it pretty much drill the hole, stick the hose in, turn it on and wait until it's fill, and repeat??? It sounds like a PITA, but easy enough. We are planning on painting the room soon, also...

Can I rent the machine, and assuming 2x4 construction and 8' ceilings, what cost can I expect per linear or sq foot?

Thanks.


Last edited by pcampbell; 11-05-2008 at 12:45 PM.
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Old 11-05-2008, 01:14 PM   #2
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DIY Blown in insulation?


Do you have any insulation in your attic? That's usually a bigger return on your investment when considering cost, time spent and heat savings.

Can't tell you how much you'll need for the walls, but I believe HomeDepot or Lowes rent the blower for free if you buy enough material. I'll bet if you contact a company that sell the cellulose insulation they can give you a pretty good idea based on your construction.

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Old 11-05-2008, 01:28 PM   #3
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DIY Blown in insulation?


This is sort of confusing for me... because someone did a very clean and neat job putting R-11 on the attic ceiling and R-13 on the walls in the attic. According to http://www1.eere.energy.gov/consumer...nsulation.html, this should be more like R-50!!!

Next, the insulation between the living area and attic is very old, and deteriorating, can't even read what it is.

In the winter, it gets quite cold in the attic, and VERY hot in the summer.

It is pertinent to note that our HVAC system (both heat and A/C) is in the attic.... so I am not sure that we really want to be separating it from the living area, so much as separating it from the outside????

Last edited by pcampbell; 11-05-2008 at 01:31 PM.
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Old 11-05-2008, 01:49 PM   #4
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DIY Blown in insulation?


Blow in is great if you have access to the whole wall. And you have it correct in the way it is done.

The problem is that if there are obstructions (previous insulation, paper, wood blocks) then the insulation will not get through the whole area. But at least you will get most of it.

Then the windows. Most of your heat is going out the windows if they are single pane. Replacing those would be the biggest bang for you buck.
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Old 11-05-2008, 09:03 PM   #5
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DIY Blown in insulation?


Sounds like you could have lots of fun projects ahead. (Attic, walls, windows?)

Not sure what type of siding you may have but if it's vinyl, get the removal tool and remove the necessary siding before drilling. The plugs aren't very attractive and depreciate the value of the home IMHO.

Personally, I've done both cellulose blown in insulation in my current attic and the walls in our previous home before we resided it. There was quite a reduction in our utility bills after doing so in the previous house.

Best of luck.
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Old 11-07-2008, 03:14 PM   #6
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DIY Blown in insulation?


I'm confused about your attic. Is the insulation between the rafters or the attic floor joists? Is the attic vented or is it conditioned? If the attic is vented then the between rafter insulation is nearly useless.

First get yourself to R50 in the attic. That's the easiest and cheapest way to save energy and increase comfort. But you need to figure out whether you have a vented attic or conditioned attic first so you put the insulation in the right place.

When you get to the walls you can blow it in from the inside by cutting holes in the drywall or from the outside after removing a piece of siding or drilling through the siding and using plugs (not very pretty).

Inside or out depends on what your skills are and where you want the mess.

And like MG said if you have single pane windows that's not good in an area that needs R50 in the attic. But to start out the attic will get you the biggest savings for the buck if all you have is R13 now.
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Old 11-07-2008, 03:44 PM   #7
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DIY Blown in insulation?


Thanks for asking. I am a bit confused myself.

Here is what I think is going on: There's some crappy old insulation on the floor joists of the attic (ceiling of my living area) from a long time ago. This would be difficult to replace with a sub-floor put down, covering 60% of the attic.

They put the central heat/Air in (furnace and all duct work are in the attic) and at the same time they put in R-11 and R-13 on the attic rafters (i.e. the roof of the house), and walls. There is no insulation anywhere else in the house.

The attic is not conditioned PER SE, that is we are not trying to keep it warm or cool actively, but with the HVAC system in the attic, I would think the attic should be kept very well insulated. As I said before, it gets fairly cold in winter, and very hot in the summer, in the seasons.

There is also a large attic fan, that results a gaping hole in the attic ceiling. If I were to insulate the attic very well, does it still need to be "vented"?

Our windows downstairs are double pane, replacement not sure what year. 2004 I think.

Last edited by pcampbell; 11-07-2008 at 03:49 PM.
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Old 11-07-2008, 03:59 PM   #8
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DIY Blown in insulation?


Sounds like the previous owners didn't understand attics and ended up spending money for no gain. If you have an attic fan venting to the outside then your attic is currently vented and that is why it's hot in summer and cold in winter. Only the insulation in the attic floor is "working". The insulation in the rafters might block a smidge of heat from the shingles but is mostly doing nothing because the attic ventilation is bypassing the rafter insulation.

You need to decide which way to go, vented or conditioned attic. You can have HVAC equipment in either. In a vented attic you'll need to be sure the HVAC equipment is properly insulated.

If you don't need the attic space your easiest option is blow in cellulose insulation to R50 on the attic floor. Make sure you have enough attic ventilation and make sure the HVAC equipment is properly insulated.
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Old 11-07-2008, 05:25 PM   #9
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DIY Blown in insulation?


I forgot to mention this is a walk up attic, there is a full staircase going up, and you can stand and walk throughout most of the attic area so we'd love to retain the use of it.

In terms of venting, I don't really know how this all works. There are 2 windows on opposite sides of the house (where, as I have seen on This Old House if the attic were properly insulated from the living area, these would be cracked open), that are kept closed. There is the attic fan that, while not running, is as far as I can tell a very large vent to the outside regardless of whether it is running or not.

The duct work is insulated, but I am pretty sure it's just R-11, whatever is standard on flex duct.

If I put R-50 on the rafters/walls, should I remove the attic fan altogether? Is there some sort of venting or breathing that needs to take place?

Thanks again from a new homeowner
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Old 11-07-2008, 05:41 PM   #10
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DIY Blown in insulation?


Quote:
Originally Posted by pcampbell View Post
If I put R-50 on the rafters/walls, should I remove the attic fan altogether?
If you put R-50 on the rafters/walls then you absolutely need to close up all ventilation and make this a nonventilated, conditioned attic.

Some folks leave a small gap for venting between the bottom of the roof sheathing and the top of the insulation with a ridge vent at the top and soffit vents at the bottom. Others just insulate right up against the roof sheathing with no venting. I hear lots of arguments about which is better so I guess maybe both work.

Either way you want to be sure you aren't venting the area below the insulation - the interior space of your attic.

Now the tough question - how are you going to put R-50 on the walls/ceiling of your attic?
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Old 11-07-2008, 05:45 PM   #11
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DIY Blown in insulation?


Is there a secret to it.. is it ridiculously thick? I'd have to rip down the existing R11...
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Old 11-07-2008, 06:08 PM   #12
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DIY Blown in insulation?


I wouldn't rip down the existing. I'd just try to figure out how to add 39 to it if possible. I think R25 fiberglass is around 8" thick so you're going to have to come up with some way to support nearly an extra foot of fiberglass without sags or gaps (which is why the floor is so easy). The loss of a foot of headspace might also affect how usefull your attic is. I suppose you could build a drop ceiling structure about 1 foot down and add the fiberglass supported by wires or sheath it. If you sheath it you could blow in cellulose.

You could go to spray foam which will get you more R value per inch and suppport itself (you'd need to remove the R11 or cover it with sheathing for the foam to stick to) but it is quite pricy.

You could attach foam board sheathing at about R10 per 2" but I've never seen anyone stack foam board 4 layers thick before and it costs nearly $20 per 4'x8'x 2" board

Or you could stick with a vented attic insulate the attic floor and build a 12" elevated storage platform (insulated underneath). This could be done by placing 2x12s on edge perpedicular to the joists. Cover with sheathing.
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Old 11-09-2008, 08:05 PM   #13
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DIY Blown in insulation?


I wonder if I should just start with closing up the attic fan. If the attic is insulated, do I need any sort of venting?

The issues I have with making the attic "vented" is the staircase not a pull down stairs... I guess we'd have to make some sort of hatch to do it properly. and then the fact that the furnace has pretty light insulation (R-11) and I am not sure how I could add more but it sounds like it would be fairly involved.
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Old 11-10-2008, 04:48 PM   #14
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DIY Blown in insulation?


Won't it be bad not to have any fresh air coming into the attic - wouldnt the furnace need some good O2 to burn (60k BTU)? Or will it suck it through those old leaky windows?
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Old 11-10-2008, 06:05 PM   #15
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DIY Blown in insulation?


If you close up the attic the only attic venting you need would be to the rest of the conditioned space to the house. Your attic stairs will provide that. I doubt the floor layer of insulation will provide much benefit so you really need to beef up the rafter insulation somehow. You'll need to be carefull about where your vapor barrier is so you don't end up with condensation. With a walk up stairs I would think the VB should be on the attic side of the rafters.

I can see why you want to be able to use the fullest amount of attic space. Those old walk up attics are nice for room. It might be worthwhile to take down the fiberglass and have the rafters sprayed with foam. Talk to a local spray foam insulation contractor about price.

It is good to be thinking about combustion air for the furnace. If you have an open walkup stairs you probably have enough in a leaky old house. If you tighten up the house it would be a good idea to have an HVAC guy confirm you have enough combustion air.

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