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Looking for advice -Interior Wall Covering over horizontal timber

Started by D L Bahler, October 19, 2018, 02:22:46 PM

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D L Bahler

OK so first, here's a picture of the wall design: 



 

That's a timber frame with horizontal timber infill. But the infill has gaps. Each timber would be secure vertically, so there's not a concern of the infill as a whole moving up and down. 

The construction method is done for architectural reasons, and the structure is to be viewed from the exterior. 

The question, then, is how to treat the inside surface of the wall? Bearing in mind this is a commercial application, so fire code must be kept in mind.
The area inside these walls will be used primarily as office space. So obviously it can't just be left open to the wind. I'm looking for some suggestions for a finish schedule that will make the wall airtight, attractive on the inside, and shed water (this last one isn't hard to solve) It would be nice to have some insulation value, but not strictly necessary.  

Brian_Weekley

Hi David,

So what would someone from the outside see?  Horizontal boards with gaps or will there be something like chinking in between the boards?  If not, I guess you would want some kind of material on the inside that you would see between the boards on the outside?
e aho laula

D L Bahler

There will be no chinking. 

In the architecture that this is replicating, this portion of the building would be a hay mow. Hence the gaped timbers for ventillation. 

I have considered simply glazing the interior walls. If not whatever material covers the inside will likely be black on the side facing the exterior so that it is not noticeable.  

The desired effect is something like this: 



 

If I can't come up with a suitable solution, I'll just eliminate the infill and cover the exterior with b+b siding

Brian_Weekley

That's kind of what I thought you might be after.  I would think you could first cover the inside with black Tyvek to act as a dark curtain between the gaps when viewed from the outside.  Then add 2 inch thick foam sheets on the inside for the insulation.  The foam could be secured/sandwiched in place with horizontal strapping screwed into the horizontal timbers (how thick are they)?  Then finish the inside with vertical T&G, shiplap, or B&B attached to the strapping?  Kind of the opposite of how I insulated/finished my barn except I used cedar shingles.

The Barn Raising... in Timber Framing/Log construction


e aho laula

D L Bahler

I have thought about this approach. 

-For the record the horizontal timbers are modeled @4" thick but my be 3" in actual application, with a span of about 7 feet- 

The concern I would have is whether such would satisfy commercial fire code. I'm dubious that wood boards over foam insulation would make the fire marshal very happy.

Of course, I could easily replace the interior cladding with drywall and that would likely satisfy the fire marshal. (sounds like a question for my architect) 

The first thing I would do is apply a moisture barrier with flashing at the bottom to direct any water or snow that is blown in back to the exterior. 

I had also thought about placing 2" vinyl or fiberglass clad polyiso on the inside as an exposed wall surface. But again, fire code. 

Hopefully we can brainstorm some solutions so I have a few options to bring to the table. 

Don P

There is not one commercial fire code in the way you are thinking so first thing is to determine construction type.
VB, 5B is unsprinklered and allows what you want, any material allowed by code, it can pretty much burn to the ground unimpeded. Residential is VB for example.
Construction type is governed by proximity to lot lines, building occupancy and use, heights and areas, zoning, etc. That will be a discussion between you, architect and building official. Delve into the IBC, This is VA, pretty stock but see if they have yours online. Start with chapters 3 and 6 but you can see there will be more,
https://codes.iccsafe.org/content/VCC2012

D L Bahler

Thanks for the info, Don

I am aware there is no single fire code applying to commercial in general. But it's also true that I don't know much about these standards. Pretty much my knowledge is limited to the fact that there are different requirements in different situations, but I don't know what defines said situations. I know what I can do in general residential construction, but have a lot to learn expanding into other areas.

To be clear, the space in question would be used as office space. But other portions of the same structure will house a factory, a retail space, a commercial kitchen, and a large assembly area.

The building will be on a rural lot, not in close proximity to property boundaries or other structures.

Don P

 I'm a residential contractor primarily so no expert here.
Can you separate the different occupancies into their own fire areas with proper separation? If not the most restrictive applies to all. The building I'm working on now is divided into 3 fire areas separated by masonry that extends from footing up through the roof to the top of the dividing parapets, which must be, ahh I think 30" above the roof surface. One area can burn without affecting the adjoining area. One is office, another probably A2, the third to be determined. This reduces area for one and also allows/ requires different construction/ protection in each area.

D L Bahler

I'm not sure if I can partition them or not, but I doubt that I can. Unless I have totally misunderstood the requirements for firewalls.

There are 4 distinct areas of the building. 3 can be easily isolated from each other, but the fourth occupies the loft above the others. The fourth also would have the most restrictive code requirements.

Below the buidling in partitioned into sections of type B, M, and F-1
The area up top is intended to be a rentable space for things like weddings. I would guess that to be A-3

Could the sections below be separated from A-3 requirements through the construction of the floor between them? 

I also believe that the size of this structure mandates a sprinkler system.

note - there is actually a section that is intended for type B office use, but may be employed in R-2 apartment use for a time. 

Hilltop366

To prevent rot I would think that there should be a gap in-between the exterior boards and any inside wall along with a flashing at the bottom to direct any moisture to the outside.

Perhaps a complete conventional wall with a low maintenance exterior siding like steel would work best but the trick will be to build the wall with siding on the outside without being able to access the outside.

How about laying out some horizontal strapping on the floor and fastening the siding to it then stand a wall section up and building the stud wall behind it then pocket screw the strapping to the studs.

D L Bahler

Don I have another question you might have some insight on, 
According to US Code Title 42 of the US Code  Chapter 126  Subchapter III § 12183 
"Subsection (a) shall not be construed to require the installation of an elevator for facilities that are less than three stories or have less than 3,000 square feet per story" 

In my case I have a 3 level structure. However, the third level is not accessible via the levels below and is functionally entirely separate, accessible only via an exterior ramp. This being the case, I am trying to determine whether I need to make provision for elevator access to publicly accessible facilities located on the second level of the structure.

Don P

I don't believe you need to.

You're deep into architect land here but good stuff to know for conversations with them and the BO. I think you need a 3 hr separation between the F-1 and other occupancies. I believe you can apply this to the floor construction above, which is probably concrete, which can be above a wood or other ceiling... not certain there. CLT's are another option but availability is not good yet. 

 This is exactly the type of construction the WoodWorks folks are trying to promote and they do offer design assistance. I'd reach out to them, but I'd like to follow along as much as you can keep us in the loop, this sounds interesting. I need to hit the hay and am fogging out right now, there's a log barn label and dismantle in my future in the morn. Ping my pm with your email if I forget tomorrow evening, I have their help desk architect's name and contact here somewhere.

D L Bahler

Yeah, I'm just trying to get my information all lined up so when I sit down with the architect, we'll need to do as little as possible. 

The F-1 will be ICF walls, which should be about 4-hour fire rating.

I'll have to look into my options for engineering the floor above. Right now it's just modeled with 6x12 bearing beams supporting common 2x12 joists

D L Bahler

I do plan to put up a project thread, by the way. But I don't want to do that until I at least have all of my timber ordered. Preferably not till I start laying out and cutting joints. For now I'd rather keep preliminary questions as separate threads, so a project thread doesn't blow up with 20 pages of discussion before any work actually begins! 

I'll continue to float some teaser pics though, so say tuned...

Don P

This might be better, I dug up the latest email from WoodWorks, this seminar was a couple of days ago but it has several links and gives some idea of what they are about. Generally glulam and mass timber topics but they have been happy to talk about heavy timber.
https://mailchi.mp/woodworks/program-update-for-the-wood-industry-august-1499021?e=d151b96bdb
I've been to several of their seminars, well done fast paced overviews, usually in a decent restaurant with time to do some Q&A or networking over lunch.

WoodWorks came out of AITC, the glulam folks. Dad was an early user so I grew up with it.  Anyway their publications page is here, they have a light paper on fire 2nd from the bottom (hit the awc links below first though);
http://aitc-glulam.org/shopcart/index.asp#design


Thinking more on your elevator question, the upper floor egress depends on use. If just maintenance personnel then not required, if it is a workplace/public then accessibility to and on any level comes into play. Remember you need 2 remotely located points of egress, only one needs to be accessible, we'll carry them out if need be. The BO and I just had that discussion and it was good news for my project, I only need one ramp I was stressing over the second but it can be stairs.

Check the particular brand and type of ICF for their fire ratings.

Check the DCA's and WCD 5 for type IV construction (heavy timber, no concealed spaces!) here;
https://awc.org/codes-standards/publications

Thinking more on type IV, not sure if you can get there with the occupancies but worth checking. Bag the light floor joists, make the floor system all exposed heavy timber on relatively wide spacings and use heavy timber decking.

D L Bahler

If I can get by with just a ramp and stairs, I'll be OK. The operating phrase being "remote access". That is there is a perfect place to put a nice ramp and for some reason I was discounting it completely. 

I'd also love some suggestions on what I can do to get a 3 hour fire rated floor. 

D L Bahler

Also in the f1 area, I can't leave the timbers exposed. BOAH code regulating the products in these facilities mandates that floor, walls, and ceiling all be surfaces that are hard, impervious, and easily washable. This will be a dairy products processing plant.

I'd love to go with heavy framing/heavy decking, but it would have to be covered underneath. (not a huge problem)

I mentioned "the floor is modeled as" to indicate that it's wide open to change. This floor isn't integral to the structure above in any way.  

Don P

The covered underneath part can create concealed spaces, the joist bays. Can the F1 be non combustible construction for the ceiling/floor and then you resume heavy timber above say a pan deck and concrete ceiling/floor ass'y? I'm not referencing anything there just bouncing ideas.

D L Bahler

would metal (like pole barn siding) applied to the underside of the flooring and coil stock wrapping of the beams work? 

If the space inside the ribs would qualify as "concealed spaces" I could conceivably apply coil stock there instead. Or vinyl

D L Bahler

I can have direct access to all stories of the building from the exterior. This is due to split grade -the ground level will be ~10 foot higher on one side of the building due either to cutting the site into the side of the hill or constructing an artificial hill depending on specifics of the site and what the civil engineer has to say. (No foundation set on artificial hill). The loft has a large covered ramp leading to it. I hadn't really bothered to think how easy it would be to to make direct access in this way, for some reason. In fact it would be easier to have the site managed in this way than what I had planned previously. Also the loft ramp has a slope (as designed right now) of 25%, so twice as steep as practical driveway slope and about 3 times the allowable slope for an accessible ramp. Making it flatter means making it longer. Making it longer by even a little bit complicates a lot of things structurally and adds a lot of $$$

I have handicap parking with direct access to the second level, I assume I do not need to construct a ramp (I really don't want to make a ramp with 10 feet of rise. That's 120 feet of run...). In this case, do I still need 2 separate stairways? I'd assume have direct exterior access would take the place of that. (Actually the way it is right now, I have 2 stairs anyway but they're not particularly far apart. landings ~32 feet from each other.)

I'm gonna forgo designing the loft space for A3 use for now. It's gonna be some time before it would be ready for that use anyway, and it would really complicate matters both in terms of construction code and zoning requirements. In this county, if the building is built an Ag zoned land and is being used for food processing I don't have to get the land re-zoned for commercial use. Add to that that the intended primary use actually falls under agricultural law. That's good news, as re-zoning around here takes AT LEAST 4 months. Since this is a low priority function (just a possible use of a space that exists as a consequence of the architecture) It's not worth spending more money to have it available from the beginning.
So I think it would be better all around to forget that. We'll call it storage space for now. (There's a big fad around here of renting out old barns for weddings that aren't NEAR meeting the code requirements for that use. The county doesn't really seem to care at all)

Another question that falls deep into architect land; I have my primary production facility, which is used for food production and thus f-1. But a lot of the area (2 out of 3 rooms) in this area are used for aging said food items. Although aging is part of the production process, could I classify these as S-2 since there is no equipment in this room? Just shelves, lights, and ventilation?  

I'm sitting up at 2 in the morning working on this. I'm too keyed up from watching my Purdue team take down Ohio State to sleep.

ScottCC

I think I would think of it like a shower wall and the wood is tile facing out.  Apply dura rock to inside of walls using the Brillo pad style ridge vent as a stand-off between the two.  Acid stain the rough side of dura rock facing out a dark mottled brown to represent hay.  On inside frame out for interior coverings using steel studs.  Used closed cell insulation a minimum of 1" to waterproof dura rock.  Anymore is for R-value.  Finish stud infill with rock wool for fire code.  Finish as desired.  For fun hang some bailing twin, crappy wood or old pitch fork between existing exterior boards and your new built up wall.  Get some spider food for kickers.
Necessity is the mother of invention.  Poverty is its big brother.  WM mp100, WM eg100, WM sp4000 chip extractor,  WM 260 molder on order ,WM electric  lt15 wide with extra track, 71 Oliver allterrain forklift, 26' flat bed trailer, road legal log arch, homemade kiln, AutoCAD lt15

Don P

We have what sounds like a similar ag exemption. Ours does allow incidental wedding or event use as long as the primary use is ag. As soon as we cross to becoming a restaurant type use we've clearly crossed the line in our law, the gray is in between. We are really just one barn wedding tragedy away from that being revisited. As this trend continues its gonna happen. If you know there is going to be a change of use I'd build to the eventual change.

We also have a rehabilitation code that kicks in with change of use of a building. Right now I'm working on a level 3 rehab, a gut job. Although there are a few outs, and there are more outs for a level 1 or 2 more minor rehab, for a good bit of it I'm bringing it up to code for current and future anticipated uses. The old adage applies, "there is no cheaper time than now".

From the sound of the ramp access, if, you cannot make that just as easy and protected from the elements while a disabled person is working in or enjoying the use of the building, then, I think there should probably be an elevator shaft planned to be brought online as needed. It can be storage rooms with removable floors until then.

Rather than going by exemption consider that your dairy processing facility is a U and the storage areas are S-2 with an A-2 above. The floor/ceiling between then becomes a 2hr assembly instead of 3 (I really think you are an F-2 or U at most rather than F-1 from your description). DCA3 has a 2 hr wood framed floor/ceiling assembly using I joists, 3/4 ply subfloor and 3 layers of 5/8 sheetrock on the ceiling with a hat channel between the first 2 layers. Fiberglass insulation in the joist bays. The lower 2 layers of 5/8 rock could go on later. A nail laminated timber floor deck might also work.

If the assembly use upstairs doesn't pan out you have a well designed hay mow (the loads are similar) that has good dust and fire separation from the dairy ops. Not a bad deal. The 2 hr floor/ceiling will also work with an R residency above.

D L Bahler

OK so here's the kicker for codes around here...

My county has no building inspectors. This is a pro development county in a pro development state. While we technically abide by the IBC, well in practical reality I can do whatever I want after the initial permitting and compliance. 

But let's clear up a few things. 

We have 2 levels + a very large open loft. 
lvl 1 has the processing and storage facilities and a retail space. 
lvl 2 is primarily office space, but has some overflow area that will probably be used as an apartment. 
The A-2 space is in the third level -the loft- so it's directly above the B and R use areas, not the U/F (started typing those letters the other way around, decided to switch them around...) and S

I can have direct access from grade on the second level where employees are working. Parking right outside the door with a nice covered walkway. The question then is, I have a direct, convenient access to both primary levels from the exterior WITHOUT needing a ramp at all, do I need to supply a ramp within the building?

Don P

I've built in places with no inspections plenty of times. I can only say I don't rob the bank because there is no sheriff in town. The law didn't change only the enforcement. I build the same either way, I don't build for the inspector. It as gotten easier in some ways, I used to have 3 sets of code books in the camper to cover the 3 major code regions. That isn't to say I love the one that prevailed.

Quote from: Don P on October 21, 2018, 10:17:10 PM
The 2 hr floor/ceiling will also work with an R residency above.


Study chapter 11 for accessibility requirements, I can read it either way, and I'm reading my state's code. The ADA is federal though. This is part of the ramp rules, you can't rise 10' in one ski slope;

QuoteIf the slope of a ramp is between 1:12 and 1:16, the maximum rise shall be 30 inches (760 mm) and the maximum horizontal run shall be 30 feet (9 m). If the slope of the ramp is between 1:16 and 1:20, the maximum rise shall be 30 inches (760 mm) and the maximum horizontal run shall be 40 feet (12 m).
Also remember that USDA/FDA need to be made happy. Visit with similar operations and engage USDA early in the process. We've looked into a small minimal milking/cheesemaking facility without the other uses. It looked like a minimum of $80-100k to get that off the ground. Not meaning to rain but do all your paperwork before committing. Have legal on call that has experience with the FDA. If they ever show up politely lock the door, call that person and do not allow entry until that person says so. That's all I better say there.

D L Bahler

$80-100K -lightweights. Triple that, and we've got a good start. 


Yeah, we've been in communication with the Indiana BOAH from the beginning. We're making sure we'll be able to satisfy both State and Federal requirements.

Also as per ramp, I've been trying to get a god ramp design to rise 10 feet, complete with 5' landings every 30 feet that adds up to 145' of total ramp run. That's a lot, and it will take up a LOT of real estate. 

If I can make my building legal by taking advantage of direct ground-level access on both levels, that would make me pretty happy. That will be something the architect will have to decide on. 

D L Bahler

Back to the OP

reviewing information both from the codes and regarding wood performance and application of code standards to log building (this isn't log building, it's structurally a timber frame but filled with solid wood so a log building is a reasonable analogy) I've determined the best approach for interior treatment would be to apply 1 1/2" thick t+g wood planks vertically, and possibly some sort of material over the inside as well (for looks). This, I think, should bring my walls up to the standards of fire resistance required by my occupancy. Actually it should bring me well above them. 5/8" type X drywall would perform similarly, but in this case due to the possibility of water incursion wood is better.  


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