DIY Attic Flooring like "Loftzone"?

[jeromedawg]

Hi all,

I stumbled across this in my FB feed (lol) and it piqued my interest and gave me some ideas as far as what I can or perhaps should consider doing in our attic: https://www.loftzone.com/


Sounds like all it is is just a raised platform/decking built over joists in the attic. And the good thing about it is that you can add more insulation in to spec. This seems like something that could be accomplished simply with 2x6s or 2x8s (?) and 3/4" plywood no? Has anyone here done such a thing?

I am also wondering in a case where an attic isn't quite as "uniform" (meaning, there are slopes, low overhangs, and narrow spaces that make it difficult to access), how something like this would work. That also begs the question on supplemental insulation (or replacing with a higher R value) particularly in those tight spots.

Here is one such example:


In this case, where there's low clearance towards the edge of the roof, what are you supposed to do as far as supplemental insulation goes? For instance, if I were wanting to blow in cellulose: would I simply just blow it in? What about if I want to keep it from spilling over the side(s)? Would I post up some plywood sheeting some of those studs to form "walls" and then cut some holes and blow in the insulation that way?

[Paper Chaser]

The make products called soffit baffles that fit in between the framing and keep insulation where it needs to be. Honestly, you don't need to go all the way to the edges of the attic with a floor product. That space isn't really useful for anything.
If you're going to do a floor, I'd keep it confined to places that I can at least crawl through. Leave the rest open to the insulation.

The product you linked seems convenient, but it's going to lose a lot of storage height in most attics. If you're able to, I'd remove any existing insulation and place rigid foam boards in between the framing as deep as you can (stacking the foam to fill the joist bay). That will give you max R value for the space and still stay below the top of the joists. Then you can lay your floor on top of the existing framing instead of raising it and losing storage space. Rigid foam won't be inexpensive, but it will give you the most R value you can get for that limited space, and it will allow you to skip buying the stilts you linked to while maximizing storage height.

Any area that doesn't need a floor put over the top of it can just be inexpensive blown in cellulose to the appropriate depth since there is no constraint for height/depth in those areas.

[jeromedawg]

The make products called soffit baffles that fit in between the framing and keep insulation where it needs to be. Honestly, you don't need to go all the way to the edges of the attic with a floor product. That space isn't really useful for anything.
If you're going to do a floor, I'd keep it confined to places that I can at least crawl through. Leave the rest open to the insulation.

The product you linked seems convenient, but it's going to lose a lot of storage height in most attics. If you're able to, I'd remove any existing insulation and place rigid foam boards in between the framing as deep as you can (stacking the foam to fill the joist bay). That will give you max R value for the space and still stay below the top of the joists. Then you can lay your floor on top of the existing framing instead of raising it and losing storage space. Rigid foam won't be inexpensive, but it will give you the most R value you can get for that limited space, and it will allow you to skip buying the stilts you linked to while maximizing storage height.

Any area that doesn't need a floor put over the top of it can just be inexpensive blown in cellulose to the appropriate depth since there is no constraint for height/depth in those areas.

So the thing about the main part of our attic is that the roof is quite high above it. I can see the foam boards making more sense in perhaps other parts of the attic where you have to crouch down or even get on your knees or belly though. I think I can "afford" to lose some space in the main area though. The bigger issue is that it's just such an awkward space to navigate. It would be nice to put some stable plywood boarding up to so you can at least navigate the attic without worrying about losing your footing and falling through the ceiling.

Speaking of R-value, is foam boarding (plus great stuff to fill any gaps) actually a viable replacement (cost wise and in effectiveness as well) over cellulose or batt insulation even if I didn't want to bother with covering up with plywood? I'm not a fan of blowing in cellulose and then "swimming" in it in the future haha. And batt insulation just bothers me when it comes to fiberglass shed. It would be nice to clean the attic up and use something a little more 'streamlined'.

Something like this? https://www.homedepot.com/p/RMAX-Pro-Select-R-Matte-Plus-3-2-in-x-4-ft-x-8-ft-R-13-1-Foam-Insulation-Board-637898/313501510

Seems like 2" gives you R13.1 so wouldn't I be able to stack 3-4 boards per bay (which is 6-8" high... current R19 insulation we have is roughly that height) and achieve a much higher efficiency? Then just seal the gaps (if necessary) and screw plywood down directly over perhaps could cut a number of 'spacers' to raise up a couple inches and then lay the plywood over? It seems like this might end up costing quite a bit more than cellulose but IIRC, it doesn't seem like it's that far off from regular batt insulation too.

[bacchi]

I put down 2x6s, filled the raised space with batts, and covered them with spare OSB and plywood. The 2x6 lumber doesn't need to be continuous; if there's any house construction nearby, you can probably get plenty of scrap to do your entire attic.

A framing nail gun is very useful.

[Paper Chaser]

Cellulose is typically the cheapest R value per inch of thickness. Rigid foam is the highest R value per inch, but more expensive.
6 inches of rigid polyiso like the stuff you linked to would be about R40. You could achieve that same R value for less money with cellulose, but it would be 12-14" deep which sounds like it would be twice as deep as the framing you have, and would require some sort of riser if you wanted to do a floor.

That's why I'd use the rigid foam to get the highest r value that you can in a tight space like under a floor, and then use cheaper cellulose anyplace without the floor. You can use plywood, cardboard, or extra rigid foam panels as a dam to keep the thick cellulose separate from the area with the floor.

Either option would be better than the R19 batts you currently have. IF this attic space is over the living area, then spending a bit more to maximize R value makes sense to me. But if it's just over a garage, then I'd worry less about maximizing r value in tight spaces, and just stick with cellulose or batts that fill the framing cavity and then lay a floor on top of that.

[ChpBstrd]

Seems like 2" gives you R13.1 so wouldn't I be able to stack 3-4 boards per bay (which is 6-8" high... current R19 insulation we have is roughly that height) and achieve a much higher efficiency? Then just seal the gaps (if necessary) and screw plywood down directly over perhaps could cut a number of 'spacers' to raise up a couple inches and then lay the plywood over? It seems like this might end up costing quite a bit more than cellulose but IIRC, it doesn't seem like it's that far off from regular batt insulation too.

Keep in mind that rigid foam insulation is impermeable to moisture. Thus you'd be installing a moisture barrier over the top of your existing insulation.

Would this be a problem? It's hard to say. The cellulose underneath the rigid foam layer will eventually compact and open up an air pocket, and maybe that would offer enough ventilation so that you wouldn't have condensation issues? Or maybe the warmer air layer under the colder foam insulation would invite the formation of condensation on the bottom of the foam board? It probably matters if the foam insulation is laid over the cellulose/fiberglass in a single 4 foot wide aisle or if you are flooring a room-sized area.

In any case, understand that moisture is constantly wicking/leaking up through your ceiling and into the attic space, and the reason houses aren't built this way is due to concerns about putting a vapor barrier on the cold topside instead of right next to the room. That said, I'm still not sure this issue is worth worrying about.

[lthenderson]

I've hauled enough stuff that was absolutely destroyed out of attics to say I think you would be money ahead to just sort through what you have so that it fits easily within your conditioned envelope. Unconditioned attics get blazing hot in the summer and very cold in the winter which is hard on materials. Combine that with insects, rodents and other things that often inhabit the attic spaces of our homes, things get destroyed in a hurry.

[jeromedawg]

Cellulose is typically the cheapest R value per inch of thickness. Rigid foam is the highest R value per inch, but more expensive.
6 inches of rigid polyiso like the stuff you linked to would be about R40. You could achieve that same R value for less money with cellulose, but it would be 12-14" deep which sounds like it would be twice as deep as the framing you have, and would require some sort of riser if you wanted to do a floor.

That's why I'd use the rigid foam to get the highest r value that you can in a tight space like under a floor, and then use cheaper cellulose anyplace without the floor. You can use plywood, cardboard, or extra rigid foam panels as a dam to keep the thick cellulose separate from the area with the floor.

Either option would be better than the R19 batts you currently have. IF this attic space is over the living area, then spending a bit more to maximize R value makes sense to me. But if it's just over a garage, then I'd worry less about maximizing r value in tight spaces, and just stick with cellulose or batts that fill the framing cavity and then lay a floor on top of that.

Seems like 2" gives you R13.1 so wouldn't I be able to stack 3-4 boards per bay (which is 6-8" high... current R19 insulation we have is roughly that height) and achieve a much higher efficiency? Then just seal the gaps (if necessary) and screw plywood down directly over perhaps could cut a number of 'spacers' to raise up a couple inches and then lay the plywood over? It seems like this might end up costing quite a bit more than cellulose but IIRC, it doesn't seem like it's that far off from regular batt insulation too.

Keep in mind that rigid foam insulation is impermeable to moisture. Thus you'd be installing a moisture barrier over the top of your existing insulation.

Would this be a problem? It's hard to say. The cellulose underneath the rigid foam layer will eventually compact and open up an air pocket, and maybe that would offer enough ventilation so that you wouldn't have condensation issues? Or maybe the warmer air layer under the colder foam insulation would invite the formation of condensation on the bottom of the foam board? It probably matters if the foam insulation is laid over the cellulose/fiberglass in a single 4 foot wide aisle or if you are flooring a room-sized area.

In any case, understand that moisture is constantly wicking/leaking up through your ceiling and into the attic space, and the reason houses aren't built this way is due to concerns about putting a vapor barrier on the cold topside instead of right next to the room. That said, I'm still not sure this issue is worth worrying about.

Ah, so it sounds like the foam could end up trapping moisture inside the joist bays where they sit (particularly if they are air sealed)? I wonder if this would be a bigger concern in areas where the humidity is especially higher. In my area it doesn't tend to get super humid. But I don't know if humidity is the main factor in this case.

[Paper Chaser]

Closed cell foam (of a certain thickness) is an impermeable vapor barrier. But to be a complete vapor barrier upon installation, it would need to be sealed along any seams/edges too. And it would need to be continuous across the entire attic floor, or fully sealed on the sides somehow to trap moisture. If you're only doing a portion of the attic floor in foam, I'm not sure it's worth much concern. Especially in a temperate climate with low relative humidity.

What you don't want, is multiple vapor barriers that can sandwich moisture and cause mold/rot problems. I definitely would not put rigid foam on top of the existing insulation and framing. But if the existing insulation is removed, I don't see a problem installing foam between the current framing, directly on top of the drywall for the ceiling below. I'd probably just cut it to fit snugly and skip sealing any edges.

What I'm suggesting is essentially this, except in a dark attic instead of a regular room:

[jeromedawg]

Closed cell foam (of a certain thickness) is an impermeable vapor barrier. But to be a complete vapor barrier upon installation, it would need to be sealed along any seams/edges too. And it would need to be continuous across the entire attic floor, or fully sealed on the sides somehow to trap moisture. If you're only doing a portion of the attic floor in foam, I'm not sure it's worth much concern. Especially in a temperate climate with low relative humidity.

What you don't want, is multiple vapor barriers that can sandwich moisture and cause mold/rot problems. I definitely would not put rigid foam on top of the existing insulation and framing. But if the existing insulation is removed, I don't see a problem installing foam between the current framing, directly on top of the drywall for the ceiling below. I'd probably just cut it to fit snugly and skip sealing any edges.

What I'm suggesting is essentially this, except in a dark attic instead of a regular room:

Thanks. I could see this getting pretty expensive though and also time-consuming as far as cutting each individual joist bay piece to "snug" fit. I'd probably also want to stack pieces to so as to achieve greater R-value. Per the picture would you do something like that AND add fiberglass batts or blown-in cellulose as well? Or just leave that and cover with plywood? Seems like you wouldn't be 'maximizing' those several inches of space in terms of insulation... I guess if there were a very limited storage area/space that I'm interested in, then this would make sense as far as spending more to maximize space. But realistically, if I gain 6 more inches, is that really *that* significant if we have a ton of vertical space in the attic already? I'll have to go back up there to get a better idea but I'm not sure it would be worth spending more to save 6"

[Paper Chaser]

In the past, you've mentioned removing the existing insulation, cleaning/air sealing, and then adding new. That's kind of the assumption that I was working under. If you're keeping the existing insulation and only adding to it then my suggestion would change.

I'd probably do 1 layer of 4" thick foam boards instead of layering 2" thick boards. They're not quite as easy to find, but they'd save some cutting time and effort. Then I'd fill in whatever gap remains with cellulose because it's cheap and easy.

Yes, rigid foam is expensive. That's why I'd limit the usage only to areas that would have a floor on top of them. If you want a bunch of R value and a floor, it's going to be expensive. The riser system is expensive too.

The product you linked to is around $220 for 64sqft of coverage, plus the cost of whatever insulation you'd use underneath which would be around 12" thick if you've got 2X6 framing and would be replacing the existing insulation.

4" thick rigid foam is $91 per 4x8 sheet near me ($182 for 64sqft of coverage) plus the cost of 1-2" of cellulose on top of that to fill the cavity. Plus you don't have to lift or step ~6" higher to get to the floor level in the attic. Even if the rigid foam were the same price as the riser system, you'd still save money by having to buy less insulation to fill back in.

Many cities also have places that sell rigid foam panels much cheaper than the Big Box stores. These can often be found on Craigslist, FB Marketplace, etc. I saved ~35% on some panels for my barn vs the box stores. It's worth a few minutes to search around and see what your options are.

If you just wanted a floor and some R value as cheap as possible, I'd DIY the riser system by using boards on their sides, keep the existing insulation, and just blow in cellulose to fill the space in between. But there are drawbacks to that:
- no air sealing or cleanup of old, dirty insulation
- Raising the floor of the attic would increase the height required to step into the space, or lift things up onto it

[sonofsven]

I wouldn't do it. The attic is best full of insulation and never visited by a human (or anything!).
If you want to add insulation I would run non paper faced batts perpendicular to your existing batts.
How big is your attic opening? Do you really want to haul building materials and stored items up there?

[GilesMM]

Unless you live in the Midwest or Arctic and have major issues with a frigid ceiling, I would leave the attic alone.  You are unlikely to make much difference to your energy bills and risk, as you mention, falling through the ceiling as well as spending money and time needlessly.  A classic FB ad putting you to work.

[affordablehousing]

Ditto, this seems like not the best use of your time. Enjoy living in the pleasure of California where even uninsulated homes do just fine, and in some ways better, since they rarely rot without any silly insulation getting wet and clogging the walls.

[jeromedawg]

Unless you live in the Midwest or Arctic and have major issues with a frigid ceiling, I would leave the attic alone.  You are unlikely to make much difference to your energy bills and risk, as you mention, falling through the ceiling as well as spending money and time needlessly.  A classic FB ad putting you to work.

I've heard that if we were to do one thing, air sealing would be the thing to look at. In our case, yes the winters aren't so bad here but the summers here can be very warm.