1921 Four Square Attic Remodel (w/ Bath!)

[Lakee911]

Hello everyone,

I'm back! Since I was last here my wife and I have had a baby (he was a big boy, almost 6mos old now, him and Mrs. Jason are well), I put an addition on our deck and replace the decking (took three months working alone here and there since Mrs. Jason and Jason, Jr. weren't able to help), and most importantly, Mrs. Jason and I decided on our next project! We're remodeling the attic to make room for two new bedrooms and a bathroom. For now it will be a guest room and my office. Current my office will be a bedroom for the next kiddo (ETA: unknown).

I thought we'd get a good start on this thread so I can set the record for longest project ever. I don't know who's setting that record right now (PC7060?), but who ever you are, watch out!

We're still working on finalizing the details, but the plan is that I'll do some demo in the attic to remove some partially started attic remodel hack-job that was started before we bought the house. Then we'll hire a contractor to put on three dormers (east, south, and west sides of the house) that match the one existing dormer (north side of the house). Contractor will selectively demo portions of our shoddy new roof and then frame, sheath, and, shingle the new dormer and roof. He'll also install the small amount of siding and trim out the soffits. I think he'll probably install the windows too, but I've not decided that yet.

Following that work, I'll hire out a crew to insulate the space. Our plan is to go with closed cell foam within the entire attic envelope. Once that's done, the partition walls get put in along with the HVAC, electrical, and plumbing. I'll hire out the plaster work and then I'll trim out the space and either install hardwood or hire out the carpet (depending on Mrs. Jason's preference). Only once the rest of the space is complete will we start in on the attic bathroom. I've chosen its location carefully due to the desired L/869 deflection .

Preliminary planning questions:

1. The existing plumbing vent passes through the attic for approx. 16" and then penetrates the roof (it comes up on an exterior wall). Once the new bath is installed, the top of the vent (outside) will be below the flood level of the highest fixture (bathroom sink). Is this a problem? Any clog and overflow would end up in the outside roof gutter.

2. Any experience to share about acrylic tubs? Are they good, bad, or ugly? Wife wants only a shower up there but I'm leaning towards a tub with a shower head. We both agreed, though, that lugging a cast iron tub up our winding steps would be absolutely no fun.

3. Should we keep the existing door to the third floor or open up the stair well to the second floor? Personal preference, I know, but I wanted to hear folks thoughts. We plan to match the exiting finishes and qualities with this new work. The attic will be on a separate HVAC system.

I think that's all for now... I'll post some plans and models of the attic once we get it finalized.

Jason

[koihito]

1) I am going to give you two answers In my neck of the woods to meet code that vent pipe would need to be extended. That said, if it's not being inspected I think with a studor vent at the sink it would function fine.

2) I have an acrylic tub in my kids bathroom and I like it. It's only about two years old but is holding up well.

3) Assuming you will have doors on all three spaces in the attic I vote ditch the door.

[PC7060]

Hi Jason, welcome back to home renovation not so anonymous! Congratulations to your and Mrs. Jason on the healthy baby. He'll be crawling pretty soon and then nothing will be safe!

Originally Posted by Lakee911

I thought we'd get a good start on this thread so I can set the record for longest project ever. I don't know who's setting that record right now (PC7060?), but who ever you are, watch out!

Hey! I resemble that remark. And if your going for the longest series of projects you'd better tighten your belt and get to work! lots of mega projects through out this site that make mine looks like weekend quickies.

Regarding the foam insulation, given Columbus isn't a super cold zone you should to consider open cell foam. Does a great job sealing up and insulating without the risk of trapped moisture between the foam and the structure.

[Lakee911]

Hey PC! Thanks for the welcome.

Originally Posted by PC7060

Regarding the foam insulation, given Columbus isn't a super cold zone you should to consider open cell foam. Does a great job sealing up and insulating without the risk of trapped moisture between the foam and the structure.

You're right, 'its not super cold here. My understanding, though, is that the open cell foam on the underside of the roof deck is a no-no. Because it has permeability, moisture from the interior space will eventually migrate through the foam to the cold underside of the roof decking where it will begin to rot the sheathing/rafters. Thoughts?

Now if we had a roof leak, open cell would certainly be in our favor. I figure that we just keep the shingles in good shape, we'll be fine. Easier said than done, I know, as the roof is typically out of sight and out of mind.

My preliminary numbers are showing less than 1 ton of cooling in the space and less than 5000 BTU/H for heating. I'm having to consider a ducted mini-split, which isn't necessarily bad, because these numbers are far less than a traditional system. This is really due to lack of windows and superior insulation. I could back down on the wall insulation (because I've got so little) but I figure that the incremental cost isn't going to be much.

Jason

[Lakee911]

Originally Posted by koihito

I am going to give you two answers In my neck of the woods to meet code that vent pipe would need to be extended. That said, if it's not being inspected I think with a studor vent at the sink it would function fine.

Thanks, Nate. Do you happen to know what code and section that is? It's not that I don't believe you because I do...it makes sense, but I've not been able to find where its disallowed.

I could use a studor vent for the sink, but the main plumbing stack vent is still of concern. They're not permitted there.

Jason

[PC7060]

My understanding, though, is that the open cell foam on the underside of the roof deck is a no-no. Because it has permeability, moisture from the interior space will eventually migrate through the foam to the cold underside of the roof decking where it will begin to rot the sheathing/rafters. Thoughts?

Jason, with any insulation you need to make sure the layer is thick enough to ensure the partial vapor pressure gradient never meets the saturated vapor pressure gradient, so there is no dew point or condensation occurring in the wall. See attached article for details.

The problem with Closed Cell is there is no way for the moisture that gets in through small leaks or is already present in the framing and masonry to disperse through normal vapor movement. As you mentioned this is especially problematic with roof where small amounts of moisture will cause roof sheathing failure over time. Remember the EFIS disasters of the 1990's?

Not saying that closed cell is bad, it just needs to be applied appropriately.

This article provide the best overall pro/con of the two type of foam insulations that I've read recently.

Summary quotes from the article:

Open cell foam is typically R-3.5-R-4.0 per inch as opposed to R-6.0-R-6.5 (aged) for closed cell foam

Closed cell foam is always more expensive per “R”. So, you could expect an R-13 of closed cell to be more expensive than R-13 of open cell.

Typical air permeance for open cell foam is around .005 L/S/M2 (liters per second per square meter) under 75 Pa pressure at a depth of 3.5”. Closed cell is less than half of that at the same R-value. Both of these rates are incredibly small and undetectable by humans without the use of measuring devices.

I've attached a photo of my crawlspace to bedroom conversion showing the before/after applying open cell foam insulation. The insulation layer is only 3" thick with a R-12 rating but made a huge difference in room comfort.

[koihito]

Originally Posted by Jason

Do you happen to know what code and section that is?

Mind you we have a few pages of "vent code" but here is an excerpt:
"Height above fixtures. A vent pipe or stack shall be at least 6 inches above the flood level rim of the highest fixture served by the vent...."

We also have a section that talks about each fixture being permitted it's own vent and arguably a pop vent should fulfill that. But I know from experience (most of my work the last three years have been hysterical historical district remodels) that our local inspectors would insist it be higher than the highest fixture. This is NC, though, and I also know from experience that code varies wildly even from county to county never mind states.

[RJCarney]

Hey Jason

Congratulations on your addition to the family! With regard to your upcoming project, please be aware of lead paint in your demolition, especially contamination to your baby. What I have found useful in circumstances like these is the use of a portable whole house fan that can be placed in a upper window, (assuming you have one in your existing attic), to keep your living in negative pressure and exhaust bad dust outside. Also the use of tack mat and anything else you can use to isolate dust from living space.

Look forward to pics and plans for your addition.

Best of luck,

[Lakee911]

Originally Posted by PC7060

Jason, with any insulation you need to make sure the layer is thick enough to ensure the partial vapor pressure gradient never meets the saturated vapor pressure gradient, so there is no dew point or condensation occurring in the wall. See attached article for details.

The problem with Closed Cell is there is no way for the moisture that gets in through small leaks or is already present in the framing and masonry to disperse through normal vapor movement. As you mentioned this is especially problematic with roof where small amounts of moisture will cause roof sheathing failure over time. Remember the EFIS disasters of the 1990's?

Not saying that closed cell is bad, it just needs to be applied appropriately.

This article provide the best overall pro/con of the two type of foam insulations that I've read recently.

Hey PC,

Thank you for the fantastic information. I’ve skimmed it for now and I’ll dive in a little deeper later. I did notice though that it said that open cell had been used successfully on the underside of roofs in Zone 5 (where I am). I’ll need to rerun my calculations, but this issue could help with my cooling load too. Right now I’m below 1.5 tons of cooling capacity which is the smallest traditional size split air conditioning system. I need a little more than half of that. I’ve yet to find a ducted mini-split that has a high enough static pressure rating for my application which won’t also break the bank. Lowering my R value may also help in that department. Some ROI involved too … calcs involved.

Originally Posted by KoiHito

Mind you we have a few pages of "vent code" but here is an excerpt:
"Height above fixtures. A vent pipe or stack shall be at least 6 inches above the flood level rim of the highest fixture served by the vent...."

Hi Nate,

Perfect. I’ll search in my code for the same or similar language. I’m sure it’s there!

Originally Posted by RJCarney

Congratulations on your addition to the family! With regard to your upcoming project, please be aware of lead paint in your demolition, especially contamination to your baby. What I have found useful in circumstances like these is the use of a portable whole house fan that can be placed in a upper window, (assuming you have one in your existing attic), to keep your living in negative pressure and exhaust bad dust outside. Also the use of tack mat and anything else you can use to isolate dust from living space.

RJ,

Thank you! To be honest with you, the thought of lead didn’t occur to me. Fortunately, though, about 98% of this project does NOT involve old paint. There is a small area that we’ll either encapsulate or test and properly abate. I’m glad that you brought it up though because it will be a concern on other projects I’m sure. What I do have to deal with though is the potential for asbestos. My attic floor is filled with a mixture of vermiculite, dense packed cellulose and fiberglass. It’s a real mess. I’ve never had the vermiculite tested, but I’ve always taken the precaution of assuming that it’s bad. That’s also one of the reasons why we’re not doing any real work to the floor (except in the bathroom). I don’t want to get anything tested that I’m unable to deal with because then not only am I obligated to disclose it but I’m also obligated to have it professionally abated at a cost of 1 million dollars *dun dun DUUN* … or so.


Thanks everyone,
Jason

PS. That’s right, CX, there are no questions here today.

[cx]

Thanks, Jason, I din't wanna hafta read it all again.

[blue_can]

Originally Posted by Lakee911

I’ll need to rerun my calculations, but this issue could help with my cooling load too. Right now I’m below 1.5 tons of cooling capacity which is the smallest traditional size split air conditioning system. I need a little more than half of that. I’ve yet to find a ducted mini-split that has a high enough static pressure rating for my application which won’t also break the bank. Lowering my R value may also help in that department. Some ROI involved too … calcs involved.

I presume you did a full manual J calculation using a model of your attic for the result? How do your values compare to the rule of thumb value of 400 sq ft/ton?

Another suggestion although not sure how feasible it would be to do this based on your current situation, is you could increase the capacity of your existing HVAC to include the additional space and then re-engineer the controls to have zones - so the attic will have its own return and supplies including a separate thermostat and controlled dampers in the supply registers to regulate the temperature in the attic independently of the main area. You may also be able to do this without upgrading your existing HVAC if your existing system is oversized based on a proper load calc.

I'm not sure how easy it would be to extend the ductwork from the main system and also you will need to perform manual D checks to make sure the existing final supply and return to the air handler is sized for the overall system.

[mullet]

Jason, glad to see you back. Can't wait to see the pics rolling in.

[Lakee911]

Originally Posted by blue_can

I presume you did a full manual J calculation using a model of your attic for the result? How do your values compare to the rule of thumb value of 400 sq ft/ton?

Yes. I did do the Manual J to compute the cooling load. I've always heard 400-600 sq ft per ton rule of thumb and I'm certainly in that neighborhood when you tweak my numbers.

The whole attic space is 952 sq. ft. but that's from where the roof hits the floor to the top peak (at approx. 105 in. in height). The volume is 3931 cu. ft. (including the dormers) and 3931 cu. ft. divided by 952 sq. ft. is an approx. average height of 4 ft. That means the rule of thumb would double because the height is only half. So, it checks out.

Originally Posted by blue_can

I'm not sure how easy it would be to extend the ductwork from the main system and also you will need to perform manual D checks to make sure the existing final supply and return to the air handler is sized for the overall system.

Not easy at all! I can't even get a return duct to the second floor without a whole lot of work and it would still be undersized and poorly located.

I do have an old abandoned chimney that goes from the basement to the attic floor. At some point it was already taken down below the roof line. It used to serve the kitchen so a good chunk of the bottom is solid. Just next to it is a laundry chute. Both would need to be completely removed to use that chase. I'm very very hesitant to tie up that space through the kitchen when we are planning a future remodel and when we don't yet have it planned. The wife might actually choose to keep the laundry chute over having more bedrooms for more children so that's tough one.

The kitchen space is already pretty cut up and I've been working on ideas/plans/sketches for two years and haven't come up with anything good. So, I hate to lock in that real estate for the duct work. Total space is about 30 in. x 17 in. so it's a good size. I'll think about it some more, though. Thanks for the idea.

My current house has a 2.5t air conditioner and while I've not yet done the manual J for the house, I'm thinking it's pretty close to being properly sized. Fortunately (and unfortunately), it's about 20-some years old and it could be ready to give up the ghost at any time.

Originally Posted by mullet

Jason, glad to see you back. Can't wait to see the pics rolling in.

Thanks. I really wish we were already in the picture portion of the timeline.

[Lakee911]

Here is where we are with the potential floor plan. I'll post more details later and describe what you're looking at it as Mrs. Jason has dinner ready now.

[RJCarney]

Hey Jason

Originally Posted by Jason

Any experience to share about acrylic tubs? Are they good, bad, or ugly? Wife wants only a shower up there but I'm leaning towards a tub with a shower head. We both agreed, though, that lugging a cast iron tub up our winding steps would be absolutely no fun.

I just installed an acrylic tub on a bath project. The designer spec'd this as the homeowners had another acrylic tub in their master and like it. I liked it as it was only 100 lbs and was on a third floor. Its by www.mtibaths.com. Nice but pricey, large selection of sizes and shapes.

Regarding your ducting issue, we did about the exact same thing on our own house 20+ yrs ago. We tore off the existing roof structure, which was a gable on a 1 1/2 storey house, cramped, clipped 2nd floor. We wanted to open things up. The existing house was also circa 1911, ballooned frame with the side knee walls extending up about 30" with an 8/12 roof, and some crappy shed dormers. We left the knee walls, removed everything else, sistered new knee wall studs to extend up to 60", framed a new gable roof with a 12/12, with 2 cross gable dormers, with the north side having flanking shed dormers.

We also had the issue of forced air heat and not good routing of ducts, so we decided to add an air handler in the attic and down feed air conditioning through out the house. I was able to stub up heating ducts in the floor of the 2nd floor, and able to stub down a/c into the upper walls of the first floor.

I put the condenser on the walk out roof deck off the back of the house to try to keep it closer to the a coil in the attic. I cantilevered brackets from the back wall to get it off the roof to minimize vibration. The plus in doing this was now the 2nd floor rooms are colder that the first floor rooms, cold a/c air is easier to drop down than to push up from the basement, but back then we put the handler up in unconditioned space, a no no by todays best practices standards. Had I known better at the time, I either would haved moved the air handler to a closet, or insulated the rafters rather than the floor.

FWIW, we also removed the masonry chimney all the way down to gain some space for a chase to run new b vent chimney up from furnace as well as plumbing and electric lines up to second floor.

A couple more thoughts, if I may, I always encourage clients to come up with a master plan for the whole house before starting any of the projects, so things can be done in a secquence that makes sense for running mechanicals, even if it means hiring an architect, then do the project in phases. Also, check with your building department to see if your floor joists will handle the new loads that a living space will put on them. I had to double up mine before we tore off the roof, and was not fun.