I spoke with a man today who would like to make a barn into a house. One of the ideas discussed in our meeting was to raise the sidewall hieght by using short(3') stick-frame walls on top of the existing barn wall plate(the wall plate currently sits 15' above the barn floor, crossbeams are at 10').
These same stick frame walls would support "standard" gang-nail roof trusses.
I imagine there will be at least two interior partition walls upstairs to give lateral support to the short stick-frame walls.
Has anyone tried raising sidewalls using this method(or anything similar) before?
Keeping costs down are a priority for this job.
Thanks in advance,
-Mark in Ontario.

Hi Mark,

I'm a little confused as to why there would be a need to add 3' wall extensions when the outside wall is already 5' high? Also, are the existing rafters supported between the wall and ridge by any type of purlin system?

Just curious,

Rudy

There are no queen posts or other intermediate rafter supports in the barn frame.
The frame is a constructed from hewn white pine(pre-1900 and definitely good quality pine), the principal framing is all around 11" square.
But it is a simple frame, even the 26' crossbeams have no intermediate posts.
The existing rafters are not suitable for the conversion(gambrel roof with plywood gussets).
I felt it would be cheaper to use conventional roof trusses than to build a timberframe roof system, including an intermediate support(queens, purlins, etc.)
However, conventional trusses would require the 2nd storey wall hieght to be around 8', as they will have level bottom chords.....although a few "raised chord" conventional trusses are being considered for the center section above the stairwell.

Maybe I'm wrong to assume that 15-20 conventional trusses would be cheaper than 15-20 rafter sets plus 8 queen posts plus 80 feet of purlin plate plus around 20 braces?

It was common around the turn of the century in the Midwest to "push up" gable roof barns into gambrels to get more room for the taller haystacks that could be made with the hay track syatems that were becoming popular. I don't know if I have ever seen a wall "extension" done to accomplish the change.

It would seem that adding a post or two under the principle ties would allow for a simple purlin system above to support the gambrel hip. The existing rafters could be used for the "lowers" and new rafters installed above the purlins. With a 5' knee wall there would be plenty of headroom and the savings in the cost of framing, siding, insulating and finishing the inside of the 3' extension plus buying all those trusses would be significant.

Rudy

The existing frame has the gambrel roof with plywood gussets, the house is to have a straight, pitched roof(9/12).
Once I see an estimate on the trusses, I'll be in a better position to figure out the cheaper route? Believe me, i would love to cut a queen/purlin system for the frame but cost is the key here.
I agree that a 5' kneewall would provide enough headroom, my concern is that the 5' kneewall would be difficult to engineer, even with queens and purlins in place.
Conventional trusses should eliminate roof thrust from the frame and then we only have to worry about the top of the sidewalls having enough stiffness to carry the trusses...which could be a problem in itself as the bay plan will be 18'/4'/18'.
However the walls are intended to be strawbale so it will be possible to place vertical posts against the outside of the existing frame(buried in the strawbale), rather than cut through the girts for intermediate sidewall posts.

The conventional truss price for 21 9/12 pitch X 32foot wide trusses is 2700-3000(Canadian$).As Rudy pointed out, the stick-frame materials and labour for sidewall extensions would be added on top of the truss price. Can this building get a timberframe roof structure for less than that?
I imagine we need:
4 lower posts
8 upper posts(queens)
2 purlins @ 40 feet
15-20 rafter pairs
20 or so braces.....
Any thoughts would be appreciated
-Mark.

Hi Mark,

For years we have been using a per board foot basis for estimating frame costs and it works well for us. Our feeling is we are timber framers so we base our price on how much timber we frame. Depending on job size, timber species and complexity of joinery we use $7-9/BF (US). I don't know how well that works in your situation but it would at least give you a WAG at the cost for framing.

The other issue you need to address is how the roof insulation sytem will work. If it's SIPs, they don't work all that well on trusses.

Rudy

Rudy:
Can you explain what you mean by: "...they don't work all that well on trusses." Do you mean standard stick build trusses or timber frame trusses?
And why?
Jim Rogers

I worked out a material list for the roof frame.
First, though I changed the bent spacing to
16/8/16
The plan is 26x40
Materials:
lower posts 4@8x8x10
lower braces 8@4x5x5
upper posts 8@7x7x10.5
upper crossbeams 4@6x8x12
purlin plates 2@6x10x40
upper braces 20@4x5x4
rafters 30@3x8x17
total board feet = 2388
multiply by $7 = $16,716
multiply by $9 = $21,492

I like this system, the price is similar to the per join price we've been working with. Thanks for the idea, Rudy.