angled floor below stairs

[SH_Canada]

the plans exam examiners are getting pickier....

 

"backyard suites" are getting popular here. These are essentially garages with a suite above. The suite above must be separated from the garage by a fire rated ceiling.

 

The problem are interior stairs. Normally one can get around this by putting a door at the top of the stairs. But in this case the customer did not want this as he wanted a pony wall

 

This then creates two problems

1. for canadaland, calculating the wall effective R value for the inhabitable space (divided by above and below stairs).

2. create a fire assembly for below the stairs to separate from the garage (normally this is avoided by enclosing the stairs). in cases where the customer wants to use below the stairs

 

My question for 1, is are people  drawing a polyline down every stair to get the value above the stair? cut one down the middle and call it a day? just calculating the wall area for both above and below where the stairs are and "giving up" the area below the stairs? In most cases the wall does not meet the req R value so by adding this area below the stairs, it makes the tradeoff calc more difficult to achieve.(need to add more attic insulation)

 

For 2, is there a way in CA I could draw an angled "floor" to run with the stairs as shown by the blue below? (the customer wanted a bathroom in the garage below the stairs). I could do it in this elevation view with CAD, but wanted to know if there is a better way. Ideally this would mimick the floor assembly to get the prescribed FR and STC ratings. so say 9" deep with insulation, channels, rated drywall. Then the polyline for 1. would also be simpler.

 

thanks

 

 

 

 

 

[Chopsaw]

35 minutes ago, jasonN said:

For 2, is there a way in CA I could draw an angled "floor" to run with the stairs as shown by the blue below? (the customer wanted a bathroom in the garage below the stairs). I could do it in this elevation view with CAD, but wanted to know if there is a better way. Ideally this would mimick the floor assembly to get the prescribed FR and STC ratings. so say 9" deep with insulation, channels, rated drywall. Then the polyline for 1. would also be simpler.

 

I think a manual ceiling plane should work fine for this situation.

 

So for question 1, do you intend to put a door at the bottom of the stairs ?

[SH_Canada]

9 minutes ago, Chopsaw said:

So for question 1, do you intend to put a door at the bottom of the stairs ?

there is one there, it is just on this side of the camera, on the outside wall

[Chopsaw]

Ok so the upstairs access is from outside only ?  Then stairwell and under side of stairs will be the fire rated barrier and division between conditioned and non conditioned zones.

 

So you should be able to just calc. the wall area above the stair level for the conditioned area I think.

[SH_Canada]

7 minutes ago, Chopsaw said:

 

So you should be able to just calc. the wall area above the stair level for the conditioned area I think.

right but how does one do that, trace the stair riser and tread/nosing for each stair? use the stringer bottom?

 

I tried the ceiling plane, looks not bad if I can change the depth of the landing to match, how does one change the landing joist depth? I tried changing the deck in defaults, no luck, the component of the landing claims it is 2x10, but a measurement on the section shows that not to be the case

 

 

[Doug_N]

38 minutes ago, jasonN said:

there is one there, it is just on this side of the camera, on the outside wall

I have another question for you.  How is the radon gas rough in accessed?

[Doug_N]

[SH_Canada]

11 minutes ago, Doug_N said:

I have another question for you.  How is the radon gas rough in accessed?

 

dont get me going on that.  The conversation with the examiner started with me saying. Do I really need radon for 20 sq ft (I originally had it in the garage and they said it could not be there)

. Then he said it had to be in the middle of the slab somewhere and the outlet could be in the furnace room.

 

I was waiting for him to tell me I had to have a FR mini door behind the toilet

 

so to answer your question.... floor hatch..but to answer it in real life. no one would care. but it is another reason why I wanted to get the FR below the stairs, so then I could say there is no part of the dwelling not isolated from the slab. He was indicating the furnace room was part of the dwelling and I said no as the ceiling was FR and then he said what about the penetrations, then I said, they can be fire stopped and it is HW heating so there are no ducts, so then he said an HRV is needed and that will need air flow .......

 

so i am looking to avoid all this with rated floor below the stairs and FR walls and FR door to the (non) furnace rom

[SH_Canada]

@Doug_N ..must be getting late for me to miss the obvious. thanks. looks good now with the ceiling plane and the landing. I suppose I could cheat and probably adjust the stringer to match as well

 

[Doug_N]

Maybe put in in the furnace room and mechanically vent to room to the exterior.  None of the air in the furnace room should get into the occupied space because of the HRV.  The tough part comes when they do a radon test and find that you have to vent the gas, and then you need to go above the roof!    

[Doug_N]

Does Alberta use the National Building Code?  In Ontario we have our own version (OBC) with lots of goodies added onto it just to make live unbearable.  SB-3 for fire rated wall and ceiling assemblies and sound transmission indexes are very helpful though.

[SH_Canada]

2 minutes ago, Doug_N said:

aybe put in in the furnace room and mechanically vent to room to the exterior. 

thats where I had proposed it, for the 6 sq ft, and he said it had to be in the "centre", so he picked below the landing.

 

The whole thing, in my view is a bit ridiculous for the tiny area as the bathroom does not count for the dwelling

 

 

[SH_Canada]

3 minutes ago, Doug_N said:

Does Alberta use the National Building Code?  In Ontario we have our own version (OBC) with lots of goodies added onto it just to make live unbearable

we use NBC tables for STC, FR, but yes we have our own version called the of the code, affectionately known as "ABC" 

 

[Doug_N]

I would have a discussion with the plans examiner.  The area under the slab is all connected, so it shouldn't matter where the radon rough in is located.

 

(I am assuming that the rough in goes through the slab on grade.)

[Chopsaw]

21 minutes ago, jasonN said:

right but how does one do that, trace the stair riser and tread/nosing for each stair? use the stringer bottom?

 

Are you insulating up into the stair cavity from the under side or just the ceiling plane framing below ?  If you are not using the stair cavity for insulation value then use the bottom of the stair stringer for the calc.  Basically an average of where you are placing the vapor barrier.

[robdyck]

7 hours ago, jasonN said:

For 2, is there a way in CA I could draw an angled "floor" to run with the stairs as shown by the blue below? (the customer wanted a bathroom in the garage below the stairs). I could do it in this elevation view with CAD, but wanted to know if there is a better way. Ideally this would mimick the floor assembly to get the prescribed FR and STC ratings. so say 9" deep with insulation, channels, rated drywall. Then the polyline for 1. would also be simpler.

I handle this type of thing with a p-solid or a 3d molding drawn in that section view. Very simple to edit if some height changes are required.

And I always start with a basic CAD mockup to ensure I have the correct layers / depths assigned. My p-solid would only be a single layer, just to show the finished depth. Actual drawing of all layers would all be cad and only in a detail of 1" scale or greater, not in a general section view. In the section view and in plan view, I would include a heavy, colored dashed line to clearly illustrate the location of separation of compartments, whether that's for fire or for conditioned space.

[robdyck]

7 hours ago, jasonN said:

The problem are interior stairs. Normally one can get around this by putting a door at the top of the stairs. But in this case the customer did not want this as he wanted a pony wall

It is always easier to include a typical exterior type of door at the bottom of the stairs. Then the separation at the stairwell is simply the wall around the stairs; a typical garage-to-house wall.

I insist on this when discussing these scenarios with the client!

If it's difficult for you to draw and detail and get through permitting, then it'll be even more difficult for the trades on site!

In the example you provided, you shouldn't need to do any detailing to the underside of the stairs; the fire / insulated separation should be the walls around the stairwell and furnace room.

 

[SH_Canada]

14 hours ago, Doug_N said:

I would have a discussion with the plans examiner.  The area under the slab is all connected, so it shouldn't matter where the radon rough in is located.

 

that was exactly my thinking. apparently not his.

"can't be in the garage", he wrote it first in the initial review and then said it when I spoke to him. Couldn't convince him otherwise.

 

Also had another interesting one on this plan. He said the laundry room door had to be 32", I said no, laundry is it's own room and does not fall under "utility" room. He quoted the oxford dictionary. I sent it to the govt of alberta. GoA came back with, it is its own room type, not a utility, doesn't need to be 32". examiner brings in his boss, his boss says, the NBC illustrated guide references W/D for utility rooms. GoA says no, original ruling stands, not a utility room. in case you are wondering why not 32. they want W/D in a bathroom in a closet with a pocket door. Not enough room for 32" pocket door

 

[SH_Canada]

8 hours ago, robdyck said:

In the example you provided, you shouldn't need to do any detailing to the underside of the stairs; the fire / insulated separation should be the walls around the stairwell and furnace room.

the kicker here was the washroom. he said that had to be isolated as well because it is not part of the dwelling, but then where does the radon rough in go.

 

but back to #1 even on a normal walled staircase for the energy calc, are you using the area of the entire exterior wall or just above the stairs or just the top level. And then for floor area, are you using only plywood(stair materials) for the energy calc for the stair opening or using the outside dims for floor area?

 

I figured if I could build a floor below the stair it would take care of the opening problem for the energy calc as well. But your point on how the heck would someone know what to build is well taken. I got it approved as it is without that, but it is a bit of a dog's breakfast, IMHO

 

In this case for the energy calc,  the city was okay with me just using the top floor of the exterior walls and using the full floor (incl the stairwell) for the floor calc. But given the pickyness of the radon rough in, I think he just missed it. But they have also not said anything for other plans submitted which i have done similarly. So i figure everyone is ignoring it, no one cares, or no one has realized it. but i could not find any doc on this scenario. There is doc for required RSI of floors over garages, but have not seen anything wrt a stairwell

 

Just wanted to know what others are doing 

[SH_Canada]

14 hours ago, Chopsaw said:

Are you insulating up into the stair cavity from the under side or just the ceiling plane framing below ?  If you are not using the stair cavity for insulation value then use the bottom of the stair stringer for the calc.  Basically an average of where you are placing the vapor barrier.

the curent design without the angled below stairs ceiling plane, would only have the walls insulated, which means the only insulation between the suite and the concrete garage floor is plywood from the stairs

 

[Doug_N]

I would create a ceiling plane below the stairs to get sufficient insulation that would match the suite floor insulation thickness, not that it is require, but it sure would make good thermal sense.   I have a BCIN HVAC designer who would do the building calcs, supply design forms and drawings for you for about $500 or so.  Adam Carter 1 905 419 1961.  Canada HVAC Design.  http://canadahvacdesign.com/. canadahvacdesign@gmail.com

 

I am sure that Adam can make some recommendations that would suffice.

[SH_Canada]

1 hour ago, Doug_N said:

 I have a BCIN HVAC designer who would do the building calcs, supply design forms and drawings for you for about $500 or so.  Adam Carter 1 905 419 1961.  Canada HVAC Design.  http://canadahvacdesign.com/. canadahvacdesign@gmail.com

thanks. I have an HVAC guy I use on commercial but he is around 1k.  your guy might be the better option.

 

My whole thinking on this is I cannot be the first person to deal with this stair in the garage thing. I see them all the time here. My guess, is the thermal piece on the stairs is being ignored on the tradeoff calc or everyone is using a model for the energy calc....and who knows what a model does with it (probably ignores it or assumes the floor thermal), because unless your (and everyone elses) guy is typing in the stair rise, run, stair thickness, stairwell opening, I cant see how the model could do it accurately either

 

[Chopsaw]

1 hour ago, jasonN said:

16 hours ago, Chopsaw said:

Are you insulating up into the stair cavity from the under side or just the ceiling plane framing below ?  If you are not using the stair cavity for insulation value then use the bottom of the stair stringer for the calc.  Basically an average of where you are placing the vapor barrier.

the curent design without the angled below stairs ceiling plane, would only have the walls insulated, which means the only insulation between the suite and the concrete garage floor is plywood from the stairs

 

Unless you have a thermal barrier I am not sure how you would work out the energy calculations.  I would agree with Doug and insulate the Fired Rated barrier otherwise you need a fire door on the bathroom by the looks of it ?

[SHCanada2]

1 hour ago, Chopsaw said:

Unless you have a thermal barrier I am not sure how you would work out the energy calculations.  I would agree with Doug and insulate the Fired Rated barrier otherwise you need a fire door on the bathroom by the looks of it ?

I have it as insulated. but i'm not sure how it helps, as the energy calc requires a calc of the floor, AFAIK. so even if the stairs have walls around it built to R100, the path of most heat loss will be through the concrete foundation below the stairs. 

 

.. or maybe the full height wall of the stairwell is used, and the concrete floor area below the stairs is calced  and referenced against a foundation floor instead of against a floor above grade . in other words calc as if the stairs are not even there. that might be the easiest of the complicated solutions.

zone 7A  floor at grade is required to have 1.96 RSI

 

looks like some funky foundation insulating work if people are calcing this way for this little space: (B below). a magic 1.2M of insulation is required.

 

Still I'm wondering if this is actually what people are doing...

 

[Doug_N]

SB-9 Requirement for Soil Gas Control.rtf

I have scanned a copy of SB-9 in the Ontario Building Code for Soil Gas Control

The only part that I can see that mentions where the radon vent is to be located is near the CENTRE of the FLOOR, not the centre of the room.  This could actually be worse for you.

 

3.2. Providing for Subfloor Depressurization

(1) Except as required in Sentence (3), granular material shall be installed below the floor-on-ground according to Sentence 9.16.2.1.(1) of Division B of the Building Code.(2)   A pipe not less than 100 mm in diameter shall be installed vertically through the floor. at or near its centre. such that

(a)       its bottom end opens into the granular fill described in Sentence (1). and

(b)       its top end will permit connection to depressurization equipment....