building code questions?

Lakesrider · 07-16-2013, 07:08 AM

So I am building an interior set of walls on a concrete slab. I was told that I had to put a piece of plastic or sill gasket under the pressure treated bottom sill. Is this correct. Is there a code that states that you HAVE to do this?

Number two question regards floor joists. I have a set of floor joists that do not end over a beam. Looks like they scabbed on another 5 foot piece of joist and used that to continue the joist over the beam and then nailed it to the butting joist that continues over the first beam and then ends over a built up beam. Looks like they missed the first beam by about 6 inches. I think because they put the beam pockets in the concrete walls in the wrong place. As Maxwell Smart would say....."Missed it by that much." Odd thing is that the joists are only around 15' long. Curious as if they would have used 16'ers they would have made the beam.

Oh and they used 2x10 joists. Span is 16' between beams two story building, and the carrying walls are supposed to be over the beams....

Mirror Lake's BB · 07-16-2013, 12:49 PM

For an interior wall I would say no to the "sill seal" or plastic. Plastic would serve as a moisture barrier under the slab. The sill seal material is for exterior walls sitting on masonry or concrete foundation wall or slab and prevents air infiltration. I would think there is a code for the exterior walls. I also don't know if PT is required for the wall bottom plate although I would consider it in a basement (possible wet area). I guess it would be called a "sill" plate if you put a typical wall bottom plate on top of that.

I don't see a second question.

Lakesrider · 07-16-2013, 07:16 PM

PT bottom plate IS required on concrete slab interior or exterior.

Mirror Lake's BB · 07-16-2013, 07:32 PM

Quote:

Originally Posted by Lakesrider

PT bottom plate IS required on concrete slab interior or exterior.

That is fine that PT IS required. If you knew this already then why would you think that plastic or sill seal is required? What would you think is the purpose. Regardless, I would use construction adhesive when securing the plate to the concrete. I would also use tapcon style fasteners.

What is your Question No. 2? Guess you got distracted by Agent 99 (?).

Lakesrider · 07-16-2013, 08:23 PM

Because I was told I had to put plastic under the PT bottom plate by the building inspector. the question on the joist is....Is a scab like that allowed in building codes or does the butt/scab connection need to be over a beam? Or is that kind of connection OK to just hang out there? I would just think that this woould increase the span too much. this is a 16' span for a 2x10 which is 15' 6" long and a scab joint to complete the 16' length. I'll take pics tomorrow.

Mirror Lake's BB · 07-17-2013, 08:56 AM

Full joists are typically lapped on a beam. Splicing a joist that cannot reach the beam in full is absolutely not permissible by code. However, since it already exists, I would doubt that the inspector would require replacement. But then again he/she may be doing a little schooling with his/her inspector badge on since it sounds like you are an owner doing your own work. A possible hint to me was the plastic under the plate; the PT plate not so much (I've seen it done with and without PT but "per code"?). If anything, he/she should require that the plate be glued when fastened which, obviously, cannot be done with plastic in between.

This goes back a few years but when I put a kitchen addition on our house (did everything but the excavation and the foundation), the electrical inspector required that I add what are called a "ball box" extension to the sides of some of my metal electrical boxes (provides more volume in the box for receptacle sized wires). Two of my uncles, who were electricians, helped me with the installation and have never heard of such a thing. I had no choice and reluctantly complied.

You can go to the township and look through their building codes. Maybe a local library has the BOCA codes to take a gander but they are a little lengthy. But then you're building a clock instead of asking for the time. Others on this forum are sure to know and will make suggestions.

Good luck.

DickR · 07-17-2013, 06:53 PM

A capillary break, in the form of a strip of poly or sill sealer, is a good idea for any wood mounted on concrete exposed to the ground. It eliminates "rising damp," the movement of moisture upward through concrete, which is quite pourous.

Kamper · 07-17-2013, 07:26 PM

Without a seal of some kind, wood against concrete can rot. If a nail is driven into it, the chemical reaction can generate enough heat to char the wood. I know this from direct personal experience when I replaced flooring in my basement. (And other interesting observations on the evolution of a summer camp into a year 'round home.)

07-16-2013, 07:08 AM	#1
Lakesrider Senior Member Join Date: Jun 2007 Posts: 2,129 Thanks: 380 Thanked 1,016 Times in 345 Posts	building code questions? So I am building an interior set of walls on a concrete slab. I was told that I had to put a piece of plastic or sill gasket under the pressure treated bottom sill. Is this correct. Is there a code that states that you HAVE to do this? Number two question regards floor joists. I have a set of floor joists that do not end over a beam. Looks like they scabbed on another 5 foot piece of joist and used that to continue the joist over the beam and then nailed it to the butting joist that continues over the first beam and then ends over a built up beam. Looks like they missed the first beam by about 6 inches. I think because they put the beam pockets in the concrete walls in the wrong place. As Maxwell Smart would say....."Missed it by that much." Odd thing is that the joists are only around 15' long. Curious as if they would have used 16'ers they would have made the beam. Oh and they used 2x10 joists. Span is 16' between beams two story building, and the carrying walls are supposed to be over the beams....

07-16-2013, 12:49 PM	#2
Mirror Lake's BB Senior Member Join Date: Apr 2004 Location: Wayne, PA & Mirror Lake Posts: 150 Thanks: 117 Thanked 17 Times in 15 Posts	For an interior wall I would say no to the "sill seal" or plastic. Plastic would serve as a moisture barrier under the slab. The sill seal material is for exterior walls sitting on masonry or concrete foundation wall or slab and prevents air infiltration. I would think there is a code for the exterior walls. I also don't know if PT is required for the wall bottom plate although I would consider it in a basement (possible wet area). I guess it would be called a "sill" plate if you put a typical wall bottom plate on top of that. I don't see a second question.

07-16-2013, 07:16 PM	#3
Lakesrider Senior Member Join Date: Jun 2007 Posts: 2,129 Thanks: 380 Thanked 1,016 Times in 345 Posts	PT bottom plate IS required on concrete slab interior or exterior.

07-16-2013, 08:23 PM	#5
Lakesrider Senior Member Join Date: Jun 2007 Posts: 2,129 Thanks: 380 Thanked 1,016 Times in 345 Posts	Because I was told I had to put plastic under the PT bottom plate by the building inspector. the question on the joist is....Is a scab like that allowed in building codes or does the butt/scab connection need to be over a beam? Or is that kind of connection OK to just hang out there? I would just think that this woould increase the span too much. this is a 16' span for a 2x10 which is 15' 6" long and a scab joint to complete the 16' length. I'll take pics tomorrow.

07-17-2013, 08:56 AM	#6
Mirror Lake's BB Senior Member Join Date: Apr 2004 Location: Wayne, PA & Mirror Lake Posts: 150 Thanks: 117 Thanked 17 Times in 15 Posts	Full joists are typically lapped on a beam. Splicing a joist that cannot reach the beam in full is absolutely not permissible by code. However, since it already exists, I would doubt that the inspector would require replacement. But then again he/she may be doing a little schooling with his/her inspector badge on since it sounds like you are an owner doing your own work. A possible hint to me was the plastic under the plate; the PT plate not so much (I've seen it done with and without PT but "per code"?). If anything, he/she should require that the plate be glued when fastened which, obviously, cannot be done with plastic in between. This goes back a few years but when I put a kitchen addition on our house (did everything but the excavation and the foundation), the electrical inspector required that I add what are called a "ball box" extension to the sides of some of my metal electrical boxes (provides more volume in the box for receptacle sized wires). Two of my uncles, who were electricians, helped me with the installation and have never heard of such a thing. I had no choice and reluctantly complied. You can go to the township and look through their building codes. Maybe a local library has the BOCA codes to take a gander but they are a little lengthy. But then you're building a clock instead of asking for the time. Others on this forum are sure to know and will make suggestions. Good luck.

07-17-2013, 06:53 PM	#7
DickR Senior Member Join Date: Apr 2008 Location: Moultonborough Posts: 749 Thanks: 4 Thanked 259 Times in 171 Posts	A capillary break, in the form of a strip of poly or sill sealer, is a good idea for any wood mounted on concrete exposed to the ground. It eliminates "rising damp," the movement of moisture upward through concrete, which is quite pourous.

07-17-2013, 07:26 PM	#8
Kamper Senior Member Join Date: Jul 2005 Location: Thornton's Ferry Posts: 1,302 Thanks: 67 Thanked 171 Times in 127 Posts	Without a seal of some kind, wood against concrete can rot. If a nail is driven into it, the chemical reaction can generate enough heat to char the wood. I know this from direct personal experience when I replaced flooring in my basement. (And other interesting observations on the evolution of a summer camp into a year 'round home.)