We have had three one storey homes and they all had attic storage above the garage.

Our home's trusses weren't built to support storage. I'm guessing that's the case with the OP's trusses, as well. Mine are only made to bare the weight of the ceiling/drywall/roofing/whatever snow is there. Anything else puts too much of a load and could cause it all to fail. On the other hand, I paid extra for my shop trusses to be built to support extra weight... There were regular trusses, storage trusses and then trusses built for livable space (like a bonus room.)

That's right roof trusses aren't not usually designed for a floor load. I suspect your other houses did not have trusses.

Your current attic will be "vented" or "ventilated", the terms often being used interchangeably.

A "conditioned" attic doesn't mean it is air conditioned, its just included within the insulated shell of the house because the insulation is at the roof rafters instead of at the attic floor and the attic space is therefore cooler than the outside and warmer than the floor below. That reduces the heat gain to the AC ducts but its probably not a common way to build in your area because it is more expensive than old attics and trusses.

Obviously, the time to discuss these issues is before the roof structure is designed.

Homeowners in New England usually expect to be able to use their attics so I have never used a roof truss and don't know if its possible to support a 20 PSF storage load on top of the bottom chords but even if it is, I suspect the bottom chord is small enough that additional framing would be needed to support a floor.

Section R807 of the Alabama Residential Building Code, (2015 IRC as amended) requires you to have a 22"x30" R.O. access hatch "located in a hallway or other readily accessible location". This hatch must be insulated and its up to you if you want a pulldown ladder but before you add one, find out how much load the trusses can support an then ask that a floor be added that is high enough to accommodate the insulation. The only opinions that matter are the truss designer and you. The contractor only needs to give you a price when he knows what needs to be done.

A plywood subfloor blocked up so as to accommodate, say, 18"-24" of blown-in insulation? That's a lot of framing and blocking dead load on those lower truss chords, not to mention materials and labor to put it in place after (?) the insulation is in place?

Your preference could have been easily accommodated if contracted for before construction started. All you needed was stick construction, i.e., no trusses and a conditioned attic. (A contractor who site-builds trusses could no doubt stick build a simple structure.)

Guess your builder never heard of Dr. Lstiburek and Building Science Corp., key advisers to the US Department of Energy's efforts in efficient homebuilding. "Vented attics" makes his "Top Ten List of Dumb things to do in the South." Building-wise that is.

At this point, as noted by the architects above, about all you can insist on is the folding stairs access. But without usable storage space, what's the point?

In our neck of the woods, basements are standard, so the issue of attic storage doesn't come up.

(Just finished my third go-round shovelling the day's 15cm of the white stuff. Alabama sounds good! )

We feel let down (and kicking ourselves) for assuming our house would have an attic (because in our mind every house does), and now that we realize how high our roof goes up, we feel like we're going to have so much wasted space/opportunity.

The garage has a bonus room and we can see the differences in the lumber used to support it. Because we have a bonus room over there, the roofline over the house was raised to match, and that's how we ended up with such a high roof.

It's one of those things you don't think of because you just don't know. We don't know about different types of roofing systems and how they can determine your homes capabilities.

So... I feel like I'm starting to realize it's not only the attic floor that would need more support... but the trusses they have built would have needed to be different. They literally just built them last week... and I have been wanting to talk to our builder about this for longer than that.

worthy - I'm not even sure if he intends to vent the attic.

This is a good view of where we feel there is space (red lines) - is the framing really so far progressed that some more support/lumber/whatever needs to be done can't be incorporated to give us a sizable attic?

Is it really too late to make it this way with attic trusses?:

*the weather has been mild and nice and great in our case, but it's an odd feeling not having a normal feeling winter. you know it's supposed to be winter but you never get to feel it!

I'd also make sure they're not ducting into the attic if it's not insulated. Here's an excellent read

Where in Alabama are you building? Unless you're in B'ham, chances are your builder is about 30 years or so behind the times when it comes to best practices regarding HVAC and weatherproofing. It annoys me to no end. BTW: It IS weird that I'm sitting outside right now, wearing a short-sleeved t-shirt, in February. I'm even hearing starting to hear crickets!

With enough time and money, anything is possible. But it appears you may not fully understand the situation.

Yes, it would be possible to sister 2X joists to the bottom chord of each truss. The 2X member will have to be sized for the longest clear span to carry the dead load and live load of an attic floor. Say the new 2X will be 2X10 spaced as the trusses are spaced, either 16" or 24" O.C.

But then, how do you get 18" to 24" of blown-in insulation into the attic floor space, and thereafter lay the plywood sheathing for the attic floor? The only way I can see to do it is to build sufficient framing and blocking on the new 2X joists to have the plywood sheathing raised at least 24". That's a lot of additional framing and blocking.

Alternatively, you could pay to have the insulation sprayed to the underside of the roof sheathing and put the new plywood sheathing directly on the tops of the new 2X floor joists. That would be simpler and quicker. And probably double your insulation expense. Plus the added expense of the new joists, sheathing and labor.

Why don't you ask your builder to give you prices for the two alternatives? Stand by for large numbers in response...

Sammy, he prides himself on building "green" and brags about the insulation he sprays. I am not knowledgeable on weatherproofing or HVAC unfortunately and we are entrusting him to do it "right." I mean, we really do think he is going to build us a great house and we do like him. He is a very reputable builder in our area and not the lowest bidder. I just don't know enough to quality-check him, we are mostly taking his word. We are in northwest AL, in between Athens and Florence. Tornadoes and high winds will be our biggest threat and I know in that case we are safest underground.

Where would air ducts go if not overhead? We are on a concrete slab.

Re: weather - we have buttercups blooming and my pets already have fleas again! It's been so crazy mild.

Virgil - what if we didn't use the spray insulation? He obviously prefers it - and I understand why, but would all that extra work you mentioned be necessary if it were blanket insulation? (Forgive me if my terminology is wrong.)

Maybe it's my eyes; I really don't see trusses.

If it's not truss after all, the ceiling joists could be beefed up and a platform built above the insulation to support a heavier load where you wanted storage.

Fibreglass batts are available with an R Value up to 3.8 per inch. So 10 inches would meet the Code minimum R38 in your zone. However, it's not a great way to insulate unless the workmanship is 100% perfect. Which it will never be.

Alternatively, you could pay to have the insulation sprayed to the underside of the roof sheathing and put the new plywood sheathing directly on the tops of the new 2X floor joists.

Even if the builder is familiar with this technique, the HVAC would have to be recalculated and redesigned, including returns and supplies to the attic. That's a heck of big attic that would now be part of the conditioned space. If I were the builder, I'd want a healthy upcharge on all this--if I'd even bother with it.
***

short-sleeved t-shirt, in February Me too! (under the parka)

Blown-in insulation and sprayed insulation are two very different processes using very different materials. With vastly different prices.

Blown-in insulation generally is installed horizontally above the ceiling in and above the ceiling joist spaces. Spray insulation is generally sprayed on the inside of the roof rafters and sheathing, and any vertical wall space above the ceiling joists.

Which is your builder proposing to use?

I'm not sure, virgil. He says he "sprays" so when I got to googling I came across blown-in cellulose and assumed that is what he was referring to.

worthy - I think you're right! Now that you say that we believe it is only rafters at this point right now.

So if that's the case - and he still insists it can't be done - *sigh* ... that's not right? Would it totally blow our budget? I'm just sitting here thinking if it takes $500 worth more of lumber then why in the world not?

You are going to have to have a sit-down, calm discussion with your builder. If the roof is framed with rafter and ceiling joists the options are improved. That said, if he framed the ceiling joists using lumber only sufficient to carry the ceiling dead load, then additional, deeper joists will be needed in the areas for the attic floor.

Without knowing what type of insulation he proposes to use, the question of a strategy for an attic floor and insulation remains open.

If you can resolve this for a $500 additional cost you will be extremely fortunate. I sense many times that, especially given his reluctance as you describe. Be nice and say lots of prayers....

Simplest solution, as suggested before, is double-up a few ceiling joists where you want your storage area, then build a platform above the blown-in cellulose--11 inches meets Code minimum-- and you're all set. If the builder refuses, you can always have it done after the house is delivered.

Thank you all. This has been very helpful. I will let y'all know how it goes! I'll be very sweet, I'm a nice gal. We've had lengthy, friendly conversations with our builder and feel comfortable just laying it all out there in a non-negative way.

The building code will require him to vent the attic probably with ridge and soffit vents.

In the blow-up photo it is obvious that he is using scaffolding to build the roof in pieces instead of lifting trusses in place so there are no manufactured trusses involved. The rafters appear to be braced at their mid span by diagonal struts from a bearing wall or beam at the center of the house. This forms a simple if not crude site-built truss.

The diagonal struts are intended to reduce the size of the rafters and probably have no effect on the attic floor structure. The attic floor joists are probably standard I-joists or 2x dimension lumber depending on their span. They should have been sized for a 20 PSF storage load unless the building department was asleep at the wheel.

Since this is not a design prescribed in the building code, I suspect an engineer had to provide a design drawing for it. If you can get a copy of that drawing it would tell us what is there. It should be in the public file or the plans department at the building department if the builder hasn't already given you a full set of the design drawings. The approved permit drawings are no doubt required to be on site and you could look at them there.

If the contractor is concerned about the space available in the attic floor for insulation it is almost certainly blown-in fiberglass but it might also be blown-in cellulose. The required prescriptive R value will be 30 unless you are very far north and then 38 is required. I'm surprised that the required insulation will not fit in the joists. Post a close up photo of the attic joists and measure their height if you can. You need to understand the existing conditions before talking with the contractor.

If the contractor is concerned about the space available in the attic floor for insulation it is almost certainly blown-in fiberglass

That's because blown fg is R 2.5 per in., cellulose R3.5. Even using the blown cellulose, the 8 1/2 in. height is likely to be higher than the ceiling joists. So if you rest an attic floor on the joists, there's not enough room for the insulation.

If you upgrade to meet the actual IEEC minimum of R38, vs. Alabama's modified R30, you'll need another 2 1/2 ins. in height.

And exceeding the code-required minimums for insulation means even higher amounts of blown-in insulation. Thus, another strategy for an attic floor is going to be required.

Highly recommend you meet the minimum insulation called for in current IECC for your climate which is R38. It's possibly cost-effective to go further with attic floor loose fill insulation. Best to go a few inches more than goal, as loose fill will settle.

Airsealing is required to make insulation effective. Recessed can lighting and attic access from interior erodes energy performance through air leaks, and is potentially a bigger concern than insulation details. I agree with your builder for not compromising the ceiling air barrier, with folding attic stairs which are notoriously leaky. If you don't invest in an airtight attic access solution, you may be better off forgetting about the storage and placing the access door on an exterior gable wall accessed by ladder. Such doors need no airsealing or insulation.

Nothing wrong with traditional vented attics with the right details. Two details you seem to have wrong already are ducts in attic and not providing enough room for attic insulation, above exterior walls. I would investigate closed cell spray foam for attic floor perimeter, above the exterior walls and foam encapsulation for attic ducts, possibly burying them in loose fill. I would also estimate a flash coat of spray foam over entire attic floor for airseal, prior to adding loose fill insulation.

For best practice vented attic floor insulation, install taped sheetrock (or taped structural sheathing) for entire ceiling before building any interior walls. This eliminates need for spray foam in attic, when the design or build team has done the right thing by specifying energy heel trusses and not locating space conditioning ducts in a vented attic.

Most importantly, ensure that green builder of yours is planning a blower door test.

I don't know where the project is in GA

It's Alabama. I can tell from the OPs accent.

*****

ensure that green builder of yours is planning a blower door test.

And meets that tough state standard of 7ach@50Pa.

Yes y'all, I'm in Alabama. Those I's are very flat. North Alabama, though. We aren't worried about hurricanes, just tornadoes.

I don't think there were structural framing plans in our blueprints? We got two exterior views, two floor plan views (one showing room layout and the other showing a simple outline of the slab measurements), and one small part shows the "roof plan."

Here are some photos from my husband's phone:

re: blower door test. I don't know if those are required, but I do know someone close to a family member that owns a business that does just that, and has offered to test our home at the end of the project. However I don't understand much about it - or what can be done if the test comes back with "bad" results.

The only relevant issue is the structural capacity of the attic joists. From the photos I would guess they are 2x8's but where the spans are short enough, they might be able to support limited storage and could be shimmed up enough for the required insulation to fit.

They are 2x8s.

Woopee...look at the skinny 2X material supporting the ridge beam. Bet we see a lot more support materials up there before the roof is finished.

Looks to me like the builder is an ole boy who has always built 'em this way, and is always gonna do so...

Springtime, what blower test results should we consider a good number?

As a reference, in Ontario, Canada, where I am, the maximum leakage by Code for a detached house is 2.5 ach @50Pa. However, a blower door test is not required if the home meets certain prescriptive standards.

Similarly, in Alabama, a blower door test is required "unless the air sealing in the home was inspected by a qualified and independent professional," (added emphasis) according to the state Energy Code Guide I linked to earlier.

It's not reasonable to expect the builder to meet a standard that you didn't mutually agree to before contracting the job.

"...in Alabama, a blower door test is required "unless the air sealing in the home was inspected by a qualified and independent professional,"

In that case, I'd for sure have a blower door test done, because numbers don't lie!

But since the state--and next door Georgia btw--allow up to 6.99999 ach @50Pa, what's the point? Hard not to meet that low threshhold.

Besides, unless the building contract says otherwise, the builder is not obligated to meet standards that the homebuyer never specified in the first place.

I suspect the builder rather than the owner provided the specifications for this house.

Someday someone will want to add habitable rooms in the attic and the 2x8 joists would prevent that from happening unless it is done without a permit and then the floor would probably be bouncy. I always assume an attic will eventually be occupied so I never use trusses and use a live load of 30 PSF. I've designed too many habitable attic spaces for existing houses to do otherwise.

It does seem like wasted floorspace opportunity while not getting cost savings of engineered trusses. On the other hand, it's rare for those spaces to be efficient with little room for roof deck insulation and poorly detailed attic knee walls.

I agree it's not hard to hit 7ACH@50, which is frustrating because enforcement is non-existent and who knows how many homes are being built below the poorest performance required by law. It's comparable to times before insulation requirements, but includes health and safety concerns, not just energy.

IECC 2012 requires 5ACH@50 for climate zones 1 and 2 while all other zones require 3ACH@50, a reasonable goal according to Alison Bailes, and Joe Lstiburek who helps explain why codes begin with meager performance levels.

Passive house, the super performance non-governmental certification from Germany sets the limit at .6 ACH@50, including moisture protection in their reasoning. That's ~5X better than the 3ACH@50 of current international limits. Many rightfully question some of the program's details but air leakage limits seem to make sense and be the goal of many high performance builders in US and Canada. We have built up to 2x tighter than passive house but I think 1 to 2ACH@50 is a reasonable target for most, given the current state of the industry.

To Sammy's point, anything other than an actual measurement, is a loophole.

Since you mentioned attic knee walls - my builder is also trying to convince me there will be no room to do something like this in my bonus room knee walls:

My plans say I'll have a 5'2" knee wall on each side of my bonus room. 3' deep. The ceiling will be 8 feet tall. He makes it sound like I will lose square footage if he doesn't leave it open which makes no sense to me. (I'm not asking for custom cabinets or drawers to be built - just for the space to be left open for us to create our own solution.)

Our compromise is that he won't finish it out until I take a look so I can see what he's talking about...

It can be difficult and/or at least costly to build cabinets INTO a "knee wall" of a truss. The engineered plans generally call for lateral bracing on that wall, which would block the openings. It could also make a proper insulation detail difficult.

http://www.greenbuildingadvisor.com/blogs/dept/building-science/what-architects-need-know-about-attic-kneewalls

Also, what you see in the other part of the attic may not be all there is to it unless "the builder is an ole boy who has always built 'em this way, and is always gonna do so". There may end up being a whole another mess of spaghetti up there to crawl through/over.

http://premiumaccess.iccsafe.org/premium/document/code/553/9838540

The Building Science article author mentions that his friends in the Northeast are often surprised that builders don't just move the building envelope to the roofline and that is my reaction too.

If the roof insulation continued to the exterior wall, the knee wall (and whatever you want to put in it) would be inside the conditioned envelope of the house. The garage roof slope is 12 in 12 and the knee wall will be 5-2 high so the headroom behind the knee wall will slope from 4-10 to 0 over a width of 4-10 so it makes sense to use it for storage or built-ins. However, the usable height of 1-0 deep built-ins would be about 4-0.

This thread, and the simple issue of a usable attic, demonstrates clearly how many ways and customs there are to build and insulate something as simple as a roof. Of course, there are building code requirements to be met, as there are for the rest of the construction throughout the house, but those can be met in a wide variety of ways. Custom and tradition always seem to win the day once construction has begun.

This is a good example of how the major needs, wants and priorities for a custom house should all be worked out during the design phase, and everything that's truly important should be included in the construction bid and build documents from the get-go.

From what we understand here, the OP has always wanted a habitable attic and requested same from the builder. Somewhere, somehow the request got lost, forgotten or overlooked.

Now the situation has progressed to the point where the construction-in-progress makes it difficult (and expensive) to respond to the OP's request.

Hopefully, a constructive meeting can take place and the necessary work can be arranged.

Good luck!

In reading the Building Science article more carefully I see that it says:

"The advice in this article doesn't apply to all architects, of course. I know many who know how to do this correctly. Some even specify the building enclosure at the roofline to avoid having the problems cited here. Martin Holladay wrote a nice little piece for Fine Homebuilding a while back showing the two ways to insulate an attic knee wall."

"2. Bring the attic inside - Insulating between the rafters simplifies the air-sealing details. Now that the kneewall is located within the home’s thermal enclosure, it’s no longer necessary to air-seal electrical boxes or access doors in the knee wall."

It is also not necessary to air-seal built-ins.

Notice that the rafters rest on top of the floor instead of on the top plate of the wall.

Your builder probably assumes you will be adding built-ins in front of the insulated drywall covered knee wall.

If the builder uses the insulation scheme shown above, you could open up the kneewalls later and build in whatever you like. But he needs to complete the framing, drywall, wiring, insulation, access panels etc. in order to get a Certificate of Occupancy. Make sure the wiring and access panels will not be in conflict with your final built-in solution.

The building inspector might allow there to be unfinished openings in the knee walls for future built-ins as long as all code controlled items were completed to his satisfaction.

"From what we understand here, the OP has always wanted a habitable attic and requested same from the builder. Somewhere, somehow the request got lost, forgotten or overlooked."

This is *exactly* what happened. :(

We are doing a walk-through with him tomorrow (Thursday).

The "bring the attic inside" picture does not accurately depict an attic room over a GARAGE.

I do not know how many of you have Swiss bank accounts, but where I come from, an additional 330 sq ft of R30 in the ceiling + another 300sq ft to make up the difference in the amount of wall insulation vs floor insulation is costly. Not to mention the continual cost to condition the extra space. Nor does it take care of eliminating the lateral bracing required by the engineer on that wall. It WILL be a significant up charge.

If the garage will not be heated, moving the line of conditioned attic space to the rafters (1) from the face of the knee wall (2) would add about 100 cu ft of fiberglass/cellulose insulation to the project. That additional cost would not be worth calculating and the bonus room would be easier to heat and more comfortable. You might even want more insulation than the code minimum.

The drywall air barrier would be easier to install and should more than pay for the additional insulation.

The OP should ask the builder to use option (1) so the under-eave space can be used for storage and it will be easier to add built-ins later.

"If the garage will not be heated" - who says they were ever planning on putting ANY of this (red X) ceiling insulation in in the first place??

25.5 x 2 x 7.3 = 372 sq ft --- (62" tall knee wall × √2 = 7.3 ft)

That is like heating and cooling an entire extra room year round! (Just to show the other perspective)

Of course, this is all just speculation since we do not know if the garage trusses were design with initial cost as a priority, or energy efficiency designed into the truss as a priority, or what is customary for this buider, etc. This is all just food for thought so that liv2tell has a better idea of the options and challenges before talking to the builder. It is not meant to be a difinitive answer to what is the BEST way, just what MAY be the "original plan as bid" VS "change order" and resulting charges.

Even If the garage is not heated or cooled, insulating it reduces the heat gain and loss to the main house and bonus room. The area you crossed out is more than half the area of the garage ceiling.

The foam is needed to seal cracks and prevent auto exhaust gasses from reaching the habitable space (no matter how unlikely that is to occur so its should be continuous from exterior wall to exterior wall.

There is no reason to think the garage roof is framed with trusses or that the knee walls would need lateral bracing.

"There is no reason to think the garage roof is framed with trusses or that the knee walls would need lateral bracing."

- except that it was already stated that it was... with a picture of the kind of "trusses" that liv2tell sees for attic trusses, compared to what was misnamed as trusses on the rest of the house.

"Even If the garage is not heated or cooled, insulating it reduces the heat gain and loss to the main house and bonus room."

Does NOT mean that it is in the original bid. It would NOT be required by code.

"The area you crossed out is more than half the area of the garage ceiling."

And yet you want to claim it would cost less than pocket change?

Liv2tell asked a question about storage in the garage bonus space but did not describe the structure (truss vs rafters).

Fred S. made comments about hypothetical attic trusses but posted an example of a rafter framed structure.

This kind of incomplete and misleading information has derailed the conversation and rendered the thread pointless.