Insulation Question.

Rich Turley

Customer wants to use attic for storage. My plan is to take sheets of OSB up for flooring. I'll have to move a good amount of pink loose fill insulation to make room, currently 6-10". I'll take it down to 3.5", then cover with the OSB. Is it okay to just redistribute the extra insulation or does it need to come out? I don't know if there is any negative affects to having too much insulation as long as the vent holes are clear for ventilation except the extra weight on the ceiling drywall.

Rich

Cole

lol, I thought I read 6'10" of insulation.

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maj

Let me see if I got this right...... You want to take away approx. 6" of insulation so you can lay down osb on top of the 2 x 4 bottom truss chord? The extra insulation that you distribute won't be a problem, but I'd be more concerned about the LACK of insulation where the floor will be. You're only going to have 3.5" of insulation where the floor will be? Don't you think there is a reason there is 10" up there now. BTW, I think 10" is a little skimpy anyway.

Not only that, but are you sure the truss can handle the extra wieght. It probably wasn't designed for storage above. It is, after all only a 2x4 correct?

What I usually do if people insist on using their dirty attic for storage, is screw 2x4's to the truss webs about an inch above the insulation, then lay down the osb.

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AtlanticWBConst

If you remove the insulation from the ceiling joists, you should add more insulation in the rafters to balance out the loss in R value that you are removing. If you add that insulation to the rafters, make sure that you also add rafter vent as well.

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AtlanticWBConst

maj: "Not only that, but are you sure the truss can handle the extra wieght. It probably wasn't designed for storage above. It is, after all only a 2x4 correct?

What I usually do if people insist on use their dirty attic for storage, is screw 2x4's to the truss webs about an inch above the insulation, then lay down the osb.[/QUOTE]"


I agree about the load....2x4 ' s not adequate for storage loads...

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maj

That's a new one to me..... You would insulate the ceiling AND the rafters? So basically the heat loss from the living area would be trapped in the attic. Not to mention the excess moisture it takes along with it!! How would the attic then ventilate since the space is now enclosed?

The attic would then be a "somewhat" conditioned space.

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AtlanticWBConst

OOPS,

Maj...Thanks for that.....

I read this thread too fast. I was under the impression that the poster was removing the ceiling Joist-insulation(attic) entirely, and then building on the joists for a platform as storage.
What I meant: if this were the case to insulate the rafters accordingly... Doh!

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Rich Turley

Yea, maybe I should be more worried about the structural issues.

Rich

maj

If it's just cardboard boxes or extra vinyl siding, light stuff like that, most likely it'll be alright. But once you provide storage space for people, it usually gets taken advantage of.

I still think you'd be better off screwing 2 x 4's to the truss webs ABOVE the insualtion, then lay down the OSB. That way the insulation will still be in place. 3 1/2" just isn't enough!!! Also, the wieght of the storage will be distributed to the web plates on the bottom chord, thus transferring the wieght up to the top chord. Kind of a counteracting effect.

I would still take precautions as to your liability should the ho overload the truss.

BTW, the reason I say SCREW the 2 x 4's to the webs???? Because if you hand nail them, you might pop some sheetrock fasteners in the ceiling below from all the pounding & vibration caused by hammering.

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bigdifficultme

Is the whole attic going to be for storage? If they only want to use part of the attic for storage I would try to lay out the attic floor in a way that you could use int. walls below for some support. How wide is the truss? I think I would use a 2x6 guled and screwed on edge. Before you put down the osb I would lay foil faced rigid insulation over the new 2x6 then screw down the osb. Here in Ma. I believe code states that attics need a min. of R-30. good luck!

karma_carpentry

This post has got me curious. To anyone who's done this kind of remod before -

How does it work to 'build up' truss bottom chords (or any joist member for that matter) ?

Can you glue & screw a 2x6 onto the existing 2x4 joist and effectively make an onsite-made glulam that's almost equal to a 2x10 ?

How do you place the fasteners, what's the schedule? Do you angle screws (or gun nails) from the side of the new top member?

If you're gluing, do you worry about planing down the members? Do you worry about clamping in any way or rely on the fasteners to provide the clamping till the glue sets?

Or an alternative plan, do you put in the new top member and then sandwich it between plywood webbing? Seems to me that would be strongest. But awfully time consuming.

reveivl

A truss is a unit, it is not a 2x4 and some webs and a.....anything. It is an engineered structural member that allows you to span further between supports and hold up a ceiling and a roof with associated live/dead loads. Unless they have been designed to be loaded on the bottom chord as is being suggested here, they should not be.

You can't 'add' to them and get what you think you wil. If you double the depth of the bottom chord do you think it is twice as strong? Wrong.

As maj says, if it's cardboard boxes full of feathers there isn't going to be a problem, but once that horizontal surface is there, we all know what will happen. Wifey will move hubby's 2000 piece brick collection up there while he's off fishing.

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maj

Absolutely, I agree. Don't build up a truss without first consulting with the truss manufacturer. 2x4 bottom chord trusses don't have big enough plates on them to support additional weight.

That's why I screw 2x4's on the side of the web for storage space.

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DaveH

You could...if possible..Span new joist from load bearing wall to wall if they are available in a short enough distance to span them. This is the only way to do this safely. The trusses will not support the weight of a couple people up there loading the brick collection much less the collection itself! I have had the opportunity on a couple occasions to repair first hand the damage done by improper bottom truss cord loading. One was just alot of clothes. The garage had to have new rafter framing installed to repair the damage. We went ahead and spanned the area with new joist in the process and created an actual storage area with a drop down ladder. The car the had parked in the garage at the time didn't fair as well...

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mas2006

With the cost of heating fuel reaching new highs do you really think it a good idea to mess with insulation R value(unless you increase it).
Permit yes/no???

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