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-   -   Did my architect get it right? (http://www.diychatroom.com/f19/did-my-architect-get-right-67581/)

stubits 03-25-2010 12:43 PM

Did my architect get it right?
 
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We are in the design stages of a three story addition off the back of our DC rowhouse. I've posted posted a number of threads along the way looking for help and have received excellent advice. Thanks! We're nearing the end of the design stage with the architect and I've got some questions, hoping to benefit from the collective wisdom of the forum here. Just so everyone knows, I've met with the City at an earlier phase and they see no problems with the project.

There's lots of quirky aspects to this project, but there's one big one. There is currently a 6' high double wythe brick privacy wall separating my property from my neighbor's, it runs right down the property line and the neighbor is adamant that we not remove it (even though legally we can). We've had an SE confirm that it is structurally strong enough for us to build on top of it, but legally we can only build on top of our half. The architect has devised this ledger system.

It is also probably important to note that all joists and rafters run north south so that most the loads are taken to the south wall where there's a typical deep footing. The architect has also included a 6x6 post at the west end of that south wall, which the ledgers will connect to, hoping to also take some of that load away from the west wall. The west wall is 2x4 framing all 3 levels and the south wall is 2x6 all 3 levels, to better carry the roof loads. The west wall “cantilevers” off the existing brick party wall with a 2x10 ledger. The ledger is continuous to the southwest 6x6 post.

So, it all looks pretty ingenious to me, but will it work? Thoughts, opinions, concerns? All would be appreciated.

http://farm3.static.flickr.com/2711/...34440257_b.jpg

http://farm5.static.flickr.com/4057/...48d329a8_b.jpg

cellophane 03-25-2010 01:33 PM

it may just be me - but is it possible to get the drawings posted at a larger size?

jlhaslip 03-25-2010 04:48 PM

which way is north/south/east/west?

Is there a specific question here?

Scuba_Dave 03-25-2010 04:58 PM

I zoomed in & I still can't read the writing

Big Bob 03-25-2010 05:19 PM

Try to post drawings in a format that can be zoomed by readers.

The only opinion that really counts is the permitting office and 98% of them just go with the sealed drawing.:eek:

Looks like you are ready to spend some big bucks for relatively a few extra SF per floor.

LOL... let me know if you want to invest in a diamond mine in (Nigeria).

hope this all works out for you.

Gary in WA 03-25-2010 09:48 PM

I think it's great that you are asking now, instead of upset later as we pick it apart..... Try holding the control key while repeatedly hitting the +/= key to enlarge, Ctrl / _/- key to reduce.

Sec. C- use sound board under the drywall in addition to 2x2 and SPF to give a thermal/sound break of studs.
OR- metal channel for same. Use a vapor retarder if required on rafter/insulation above bedrooms. How are you venting attic? Double rim joists at party wall. Foam board at N/S wall exterior perimeter for thermal/capillary break from water reservoir bricks.
Be sure to verify real ply, not OSB everywhere. Roxul instead of glass batts. Basement entry- 45* the corner off the full height cabs for more room, OR swing door in from other jamb. Under slab- add 24" of rigid foam insulation for your area as thermal break to patio/walkway. Swing bath door other jamb so as not to see toilet from kitchenette and more privacy feeling. Add capillary/thermal break at 2x10/concrete.

Be safe, Gary

stubits 03-26-2010 06:47 AM

Ok folks. First thanks for weighing in, much appreciated. Second, check out my original post, I've increased the size of the images. Hopefully this helps!

Big Bob- True, it is a small amount of space, but there's not so much of that to go around here in DC. This is important space for us, so it is worth it. Plus, I am planning to do most of this myself in hopes of saving at least a little bit of $$$.

jlhaslip - In the first image, you're looking north, the second image has the compass. As for questions, I am curious if the ledger system called for by my architect should work. How about her calling for the 6x6 corner post? Plus any other thoughts or comments about anything!

GBR - Thanks a ton, this is exactly the sort of feedback I am looking for. You're right, would rather have you guys tear this apart NOW, than after I've built it. It doesn't show it on this set of plans, but rather than venting the attic, we are sprayfoaming the underside of the roof, which is acceptable here. Not sure I understand the insulation under the slab. Are you suggesting a 2' layer of insulation be laid down before the slab is poured? Seems like a lot of insulation.

Scuba_Dave 03-26-2010 08:08 AM

Is your rowhouse only betwen the 2 metal fences ?
So the deck on the right is not yours ...and you are adding a deck ?
I can understand adding on a small area if that is the case
Are you doing a flat roof ? I see shingles spec'd
Too bad your neighbor doesn't want to enclose their area too

Is that 30" door in the basement to the kitchen pre-existing?
If at all possible I would go 32" min....36" better for moving appliances in & out
If you have concrete floors in exisitng structure you may want to soundproof between floors to cut down on sound

The more insulation you can put in the better
I insulated my garage foundation, no plans to heat it...but If I ever do the insulation is there

stubits 03-26-2010 08:30 AM

Thanks Dave!

Yep, that's correct, just between the two fences... all 16' of my little lot!

So, the deck to the right is not mine, but I am building one. I only uploaded 2 out of about 20 pages of drawings and plans, so there's lots that is not shown.

The roof has a 2:12 pitch, we might push it to 3:12, but the architect is insistent that we use shingles. She's shown me that the IBC/IRC allow shingles for anything 2:12 and above, and lots of shingles are approved for 2:12 use. We'll use 2 layers of #15 felt AND we'll apply ice and water shield to the whole thing. Also, rather than venting the attic we'll apply spray foam to the underside of the roof, an allowable practice here. Are shingles a really bad option here? Not sure why she wants them so bad.

That doorway is existing and set in stone, or brick, really, as they say, not much to do with it now.

We'll definitely insulate the foundation, but 2' seems like a lot, I've never seen that before. Is that standard?

Scuba_Dave 03-26-2010 09:21 AM

I'm not sure what GBar is referring to with 24" of foam
Maybe he only meant 2-4" ?

stubits 03-26-2010 09:27 AM

Would make more sense to me!

Gary in WA 03-26-2010 08:54 PM

Lol, that would be pretty thick! http://www.energysavers.gov/your_hom.../mytopic=11490

Depends on your heating degree days: http://www.energycodes.gov/support/slab_faq.stm


Be safe, Gary





stubits 03-27-2010 07:39 AM

Thanks Gary! Got it.

So, more on the 6x6 and the ledger and the like, here's what my architect has to say:

"All joists and rafters run north south so that most the loads are taken to the south wall where we show a typical deep footing. I also show a 6x6 post at the west end of that south wall, which the ledgers will connect to, hoping to also take some of that load away from the west wall. The west wall is 2x4 framing all 3 levels and the south wall is 2x6 all 3 levels, to better carry the roof loads. The west wall “cantilevers” off the existing brick party wall with ledgers. There is a 2x10 ledger at each of the 2 heights in the brick wall. The ledgers are continuous to the southwest 6x6 post."

Does that make more sense than my explanation? Will this setup work the way she is describing it?

I guess I am also curious about:

1) The only load that the turned-down footing on the west side was intended to bear is the wall on the basement level, however the sheathing and siding is continuous to the other levels which load onto the side existing brick walls. Does there need to be some sort of separation or expansion joint between the top plate of the basement wall? Or should we not worry about this idea of bridging and just let the west wall carry all that load?

2) Is it okay for a turned down slab to butt into a deep footing, or do I need to ask the architect to add more notes about how to make that connection?

Thanks!

Gary in WA 03-27-2010 01:43 PM

1. Sounds like the S.E. has it figured out, not much load on the west wall. One rim is fine. Use a capillary /thermal break under the p.t. bottom plate of the stud wall and for 2x2 sleepers on the concrete. Also at ledger/concrete. Re-checked, in her notes.... Have specifics on bolting size, spacing, length, of ledger in concrete/brick which may be listed elsewhere...
2. The local Building Department will have final say. The joist set-up sounds fine for my limited framing experience, 37 years, though not a S.E.

Be safe, Gary

stubits 03-29-2010 08:10 AM

Gary-

35 years of experience building the stuff that architects and SEs draw says a lot and your opinion is very much appreciated.

So, do you think I need some sort of separation or expansion joint between the top plate of the basement wall? Or should we not worry about this idea of bridging and just let the west wall carry all that load?

Would also appreciate your and anyone else's thoughts on the foundation. It is a bit unique because we're a rowhouse and building right along the property line. So, on the west wall you'll see a turned down slab footing... the idea is to start it at the same depth as my neighbor's footing (his house/property is about 1' lower than mine) and step it up. On the south wall, we'll do a typical footing. What are your thoughts on this setup? How exactly will the two butt up together? I am including another drawing with some additional detail on the foundation, combined with the ones above.

Thanks!http://farm3.static.flickr.com/2740/...0417b987_b.jpg


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