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Old 05-16-2019, 08:59 AM   #16
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Re: Attic flooring: Ok to flush cut joist hangers that are sticking up?


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Originally Posted by JIMMIEM View Post
Check out getting an energy audit through your utility company. I'm in MA too and use National Grid which is hooked up with energy auditors. The audit will address insulation issues and have contractors that will do the insulation work for little or no cost. My neighbor just had insulation added to his attic and basement at no cost to him. Part of attic insulating is air ceiling attic penetrations.
at no cost to him? So who is paying for it, the taxpayers of MA? Curious how that works.

Most folks that say "Free" or "no cost" need to look deeper. It seldom is.

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Old 05-16-2019, 10:03 AM   #17
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Re: Attic flooring: Ok to flush cut joist hangers that are sticking up?


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at no cost to him? So who is paying for it, the taxpayers of MA? Curious how that works.

Most folks that say "Free" or "no cost" need to look deeper. It seldom is.

There is a small monthly fee added to every National Grid utility bill. This money is used to pay for the work. I'm specifically talking about National Grid. I don't know about other utility companies.
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Old 05-16-2019, 10:11 AM   #18
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Re: Attic flooring: Ok to flush cut joist hangers that are sticking up?


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at no cost to him? So who is paying for it, the taxpayers of MA? Curious how that works.

Most folks that say "Free" or "no cost" need to look deeper. It seldom is.
Some one is paying for it but if is there for the taking, then you may as well take it. Power companies may find it cheaper than building more infrastructure to bring in more fuel.
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Old 05-16-2019, 12:22 PM   #19
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Re: Attic flooring: Ok to flush cut joist hangers that are sticking up?


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Engineers have a habit of saying no to things so you want to have few ideas in your pocket so maybe he would like one.

Are looking at a floor for the whole area or just a storage area? of what size?
Well I was planning on maybe 16'x16' to start, but now I'm "spooked" into just putting up 8'x8' for now.
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Old 05-16-2019, 12:28 PM   #20
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Re: Attic flooring: Ok to flush cut joist hangers that are sticking up?


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Well I was planning on maybe 16'x16' to start, but now I'm "spooked" into just putting up 8'x8' for now.
you have 2x8s now if you went between them and added a 2 ply 2x10 beam in three places and built your 2x6 floor above that you would not be adding any weight to the ceiling. 2x6 over 8 ft might be light for a floor but just for storage.
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Old 05-16-2019, 02:52 PM   #21
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Re: Attic flooring: Ok to flush cut joist hangers that are sticking up?


Keep in mind that any insulation value LOST by compressing the few spots of "poking up" batts should be more than balanced by the overall additional insulating value gained from the flooring you will be adding to the joist structure.

Obviously, you can run the numbers to quantify it to the gnats whisker, but I honestly do not believe it's worth a moments worth of worry or concern. Your energy bill will never show the impact in any measurable value.

If you're really worried about the energy value, sister up some 2x6" to gain the 2-3" additional height you need, and cut some 2-3" thick closed cell foam board to fit between the newly sistered joists, and then floor over that. No doubt, this adds to the cost, but then you still get your leveled joist structure with good flooring over it to safely walk around, all the while with a nice little increase in thermal insulation for your effort. I bet you WOULD see the positive impact of THAT approach on your monthly bills!

Also, here are two additional comments regarding structural integrity.
1) The addition of the flooring will create a more cohesively stiffened joist structure, so it should be more than adequate for supporting the typical 10lb/sqft live load spec for attic spaces, even with the additional weight of the flooring.
2) You've not mentioned yet what flooring you are planning to use. 3/4" CDX is probably overkill, so I would suggest that you use either 5/8" OSB or 5/8" CDX... the OSB will have greater stiffness and should be more than adequate for your attic needs.

FINALLY... don't be spooked by the job. If you need the full 16'x16' space, then do it! I firmly believe that you won't be compromising your structure... ESPECIALLY if you sister the joists for additional insulation height!

I have recently done a full attic re-modeling/re-flooring which involved the relocation of purlins, a new knee wall installation, inserting new 2x10 joists between the existing 2x10 @ 24"oc, ending up with a series of 2x10's @ 12"oc, and decking with 3/4" CDX. My live load rating increased from the nominal attic design of 10lbs/sqft to an acceptable 30lbs/sqft so that it can be converted into another bedroom or office by whomever buys the house. Pictures of my project are in my album.
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Old 05-16-2019, 05:40 PM   #22
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Re: Attic flooring: Ok to flush cut joist hangers that are sticking up?


I never liked the look of CDX, nor OSB, and to make it nice[er] looking with a single layer, I went with an overkill of 3/4" plywood underlayment. More than silly for what I was trying to accomplish, but I liked the look of it and the over-engineering notion of no drop-outs in the layers.

Silly, I know, but I could live with the cost increase. Plus, sliding things around on CDX can be a tad rough on certain objects.
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Old 05-17-2019, 09:56 AM   #23
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Re: Attic flooring: Ok to flush cut joist hangers that are sticking up?


Forgive me... I know I said CDX, but what I meant was sanded BC ply. I agree with you completely on the CDX assessment -- I wouldn't use it either, and didn't in my own project. When I did the new floor in my own attic renovation, I used 3/4" underlayment as you did, sanded down all of the surface irregularities with 100 grit on my 4x24 Bosch belt sander, and then my wife put down two heavy coats of flooring paint. I then paneled the walls with 1/4" birch ply and installed a motion-activated wall switch for the two new LED shop light bars. The final appearance is super well-lit, very nice looking, very clean, very neat, and super easy to keep clean. Among ourselves in the family, we boast to one another about having the nicest attic in our neighborhood of over 850 homes. Aside from the heat, it is a true pleasure to either move something into or out of the attic.
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Old 05-17-2019, 12:36 PM   #24
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Re: Attic flooring: Ok to flush cut joist hangers that are sticking up?


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Forgive me... I know I said CDX, but what I meant was sanded BC ply.
No worries. I swap words myself time the half. My kids bust on me for it.

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I agree with you completely on the CDX assessment -- I wouldn't use it either, and didn't in my own project. When I did the new floor in my own attic renovation, I used 3/4" underlayment as you did, sanded down all of the surface irregularities with 100 grit on my 4x24 Bosch belt sander, and then my wife put down two heavy coats of flooring paint. I then paneled the walls with 1/4" birch ply and installed a motion-activated wall switch for the two new LED shop light bars. The final appearance is super well-lit, very nice looking, very clean, very neat, and super easy to keep clean. Among ourselves in the family, we boast to one another about having the nicest attic in our neighborhood of over 850 homes. Aside from the heat, it is a true pleasure to either move something into or out of the attic.
Oh man, now I'm internally compelled to broaden this thread to many other questions of mine. ..... Well, ok then:

Logistical questions/notes: I'm assuming then that you didn't leave any gap between the boards(?) It's suggested by sites online, but

1. I can't see how much expansion can actually happen even though the attic is ridge vented to the outside and thus experiencing outside air. (I'm wrong, I suppose?) Does the paint stop that?

2. I can't live withe the gap "look" and "feel". Is that more of my known propensity for overkill?

3. In the case where someone *does* put in gaps (such as elsewhere in the house), how on earth do they keep things lined up when 16oc and 24oc even divide exactly? Are they custom trimming each board down a blade-width?

4. Getting through the attic door: Since this isn't a living space, I was going to have these cut down to 4x2, but unless I cut them the non-structural short way across the 4', it won't line up tightly. So I was thinking on cutting them vertically into two 8' x 2315/16" (blade width / 2), and pushing them tightly together so that the boards are effectively 96"x477/8".
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Old 05-17-2019, 12:54 PM   #25
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Re: Attic flooring: Ok to flush cut joist hangers that are sticking up?


Maybe some would care to explain the need for a gap, we use plywood because it stable, with floors we glue it to the joists, Do we expect it to slide if it expands.

With floors we use T&G and when we don't have T&G we put blocks under the joint so the 2 sheets act as one when you walk on the edge. 50 years ago, plywood was new to houses and they never had T&G or blocks, they is not a lot of bending when you walk on 3/4 plywood.
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Old 05-17-2019, 12:59 PM   #26
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Re: Attic flooring: Ok to flush cut joist hangers that are sticking up?


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at no cost to him? So who is paying for it, the taxpayers of MA? Curious how that works.

Most folks that say "Free" or "no cost" need to look deeper. It seldom is.
Well, let's look deeper! The reason these energy retrofits are not charged is to encourage people to take them. Why? Because it's considered a benefit to all the ratepayers if the utility can lower the amount of energy used. Sounds counter intuitive right? You'd think an energy company should want to sell more energy, but the reality is that they'd have to invest in more infrastructure that is very expensive. So, by getting customers to be more efficient they get to reduce their infrastructure costs and thereby reducing costs overall which should translate to lower bills all around. ...or at least that's how it's supposed to work in general. I have no idea of how the numbers are working out for this specific utility.
There's often a huge payback for small upfront costs that people don't often consider. Vaccines are a few bucks, but the diseases they prevent can cost thousands to cure or more thousands in lost opportunity when people are ill, disabled, or die.
Another one is giving housing to the chronic homeless alcoholics and letting them drink there. OMG! Paying a drunk's rent and not making them quit?! Yep. Because on the street they get drunk, fall down, and someone calls 911. Emergency services and ER trips are expensive but that same person drinking in their little apartment and going to bed is much much cheaper for the taxpayer. As an added benefit, with stable housing sobriety success rates are much higher. ...but people get really mad when they think they're paying other people to "party", so most places keep their drunks on the street running up huge expenses and not helping people in the end.
But anyway...go ahead and clip back those tabs that are sticking up, don't stress too much about pushing down a couple spots of insulation sticking up, and maybe just write something on the edge of the plywood warning anyone that the storage has a very low weight limit.
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Old 05-17-2019, 06:19 PM   #27
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Re: Attic flooring: Ok to flush cut joist hangers that are sticking up?


Free advice is worth what you pay for it.

Do they have zoning laws in MA? If they do what you are proposing needs to be done with permits and drawings approved by an Engineer.

If you go ahead and pull the trigger on the modifications, and there is ever a problem, you're liable. Just you, nobody here that's giving advice.

Good luck.

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Old 05-18-2019, 06:27 AM   #28
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Re: Attic flooring: Ok to flush cut joist hangers that are sticking up?


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Free advice is worth what you pay for it.

Do they have zoning laws in MA? If they do what you are proposing needs to be done with permits and drawings approved by an Engineer.

If you go ahead and pull the trigger on the modifications, and there is ever a problem, you're liable. Just you, nobody here that's giving advice.

Good luck.



Henry, do you really think anyone is going to get fined or sued for laying some plywood in their attic to store Christmas decorations?


He does have fully supported 2x8 ceiling trusses. Many homes floor trusses where built using 2 x 8's


I wouldn't consider this a structural change requiring a permit.
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Old 05-18-2019, 10:16 AM   #29
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Re: Attic flooring: Ok to flush cut joist hangers that are sticking up?


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Henry, do you really think anyone is going to get fined or sued for laying some plywood in their attic to store Christmas decorations?
Not unless the ceiling collapses from the 2x6's and sheathing that Neil is suggesting.

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I would put in 2x6 floor joists the other way ....
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He does have fully supported 2x8 ceiling trusses. Many homes floor trusses where built using 2 x 8's
I may have missed it, but pretty sure we don't know the span, or the type / grade of the 2x8's. Without knowing those two things, nobody here knows what the related capacity is.

Here's the span tables for ceiling joists... check it out: http://www.southernpine.com/app/uplo...e15_060113.pdf

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I wouldn't consider this a structural change requiring a permit.
The jurisdiction makes that call. We can't have new shingles installed on a roof here without getting a permit.

Folks jump into these threads giving advice before knowing the facts.

The OP's attic joists may in deed be adequate for holding considerable weight, or it may not, but without knowing the span or the material type/grade, we really don't know.

Even then, the OP is in MA. Snow loading and other environmental loads need to be considered.

And the fact that the builder used 2x10 joists for 2x8's makes you wonder what other variations they did.

So the default answer is the structure can't handle any additional weight.
At least that's the answer until the data needed to evaluate it is given. Why? Typically builders don't overbuild a structure... that's throwing profit out the door.

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Old 05-18-2019, 11:02 AM   #30
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Re: Attic flooring: Ok to flush cut joist hangers that are sticking up?


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Not unless the ceiling collapses from the 2x6's and sheathing that Neil is suggesting.





I may have missed it, but pretty sure we don't know the span, or the type / grade of the 2x8's. Without knowing those two things, nobody here knows what the related capacity is.

Here's the span tables for ceiling joists... check it out: http://www.southernpine.com/app/uplo...e15_060113.pdf



The jurisdiction makes that call. We can't have new shingles installed on a roof here without getting a permit.

Folks jump into these threads giving advice before knowing the facts.

The OP's attic joists may in deed be adequate for holding considerable weight, or it may not, but without knowing the span or the material type/grade, we really don't know.

Even then, the OP is in MA. Snow loading and other environmental loads need to be considered.

And the fact that the builder used 2x10 joists for 2x8's makes you wonder what other variations they did.

So the default answer is the structure can't handle any additional weight.
At least that's the answer until the data needed to evaluate it is given. Why? Typically builders don't overbuild a structure... that's throwing profit out the door.

the man was asking for ideas and he said he was going to talk to an engineer
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