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Looking for feedback on a simple frame

Started by MatthewMeredith, July 24, 2018, 03:46:40 PM

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MatthewMeredith

Hello all,

My wife and I have been dreaming of building a timber frame home with straw bale infill walls. In the July 2018 issue of Fine Homebuilding, there is a 960 sq/ft house that checks a lot of boxes for us (floorplan, shed roof, small, simple). However, it's just a stick framed house.

I've done mortise and tenon joinery in a shop, but I've never done the actual planning and design. I have attached a few pictures of my SketchUp plans and was hoping for an experienced critique!

Here's the house: http://www.green-building.com/projects/summer-lake-residence/

And here's the first iteration of my plans:


 


 


 

Posts as of right now are 8x8, beams are 8x12, and rafters are 2x12. If the rafters are scarfed at each upper beam, the longest span is 16'. Are 2x12's on 2' centres overkill? Roof material will be metal.

There are a couple places where knee brace mortises are a bit too close to beam mortises, but those can be shifted. I have the right angle legs of the knee brace (the post and beam) at 2' right now - is there a standard size for that?

Thanks very much for any input!

Ljohnsaw

Matthew,
I was able to look at your view but I expect them to disappear very soon.  You are not supposed to link to outside web sites for pictures.  You need to post them in your gallery.  There is a post detailing how to do it but it is pretty simple now.

Interesting view from the bottom!  Are you using the web version or do you have a standalone copy of SU?  If you are going to do real mortise and tennon joints, you will need an owned version so you can add the TFRubies tools.  Makes it easy to do the joints (steep learning curve, though).

Jim Rodgers will be along shortly to comment on "standards" for joints and braces. (search his name and timber frame)  I make my braces as long as possible where they don't interfere with the use of the building (windows/door/walkways).  Short braces act as levers on the joint with the fulcrum close to it.  As far as you sizing goes, you need to do the calcs and can use the little red toolbox on the bottom of the list on the left to help with the beam numbers.  I take it no snow load?  Sheet goods/insulation under the metal?  Are you going to be filing for a permit?
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Ford 545D FEL, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 42" capacity/36" cut Bandmill up to 54' long - using it all to build a timber frame cabin.

MatthewMeredith

Quote from: ljohnsaw on July 24, 2018, 04:04:05 PM
Matthew,
I was able to look at your view but I expect them to disappear very soon.  You are not supposed to link to outside web sites for pictures.  You need to post them in your gallery.  There is a post detailing how to do it but it is pretty simple now.

Interesting view from the bottom!  Are you using the web version or do you have a standalone copy of SU?  If you are going to do real mortise and tennon joints, you will need an owned version so you can add the TFRubies tools.  Makes it easy to do the joints (steep learning curve, though).

Jim Rodgers will be along shortly to comment on "standards" for joints and braces. (search his name and timber frame)  I make my braces as long as possible where they don't interfere with the use of the building (windows/door/walkways).  Short braces act as levers on the joint with the fulcrum close to it.  As far as you sizing goes, you need to do the calcs and can use the little red toolbox on the bottom of the list on the left to help with the beam numbers.  I take it no snow load?  Sheet goods/insulation under the metal?  Are you going to be filing for a permit?
John, thanks very much for your reply! I'll get those pictures fixed asap. I'm just using the web version of SketchUp as I work from a Chromebook and they unfortunately haven't released a native version as of yet... I've played with the TFRubies stuff though - so cool! When I finalise a design I'll definitely be using that again.
I've read through most of the stickied posts from Jim; what a wealth of knowledge! Yes, blocking windows is a bit of a concern and I'll have to alter the original plans as they had a few corner windows that won't work. Snow load will be very very minimal - Vancouver Island or one of the smaller Gulf Islands. Yes, for the roof I was thinking plywood and metal on top of the rafters (are they still called rafters on a shed roof?) and 8-10" rigid insulation between rafters with gyprock to finish.
Timbers will all be Doug Fir as it's abundant here and relatively cheap.

Hilltop366

Hi MatthewMeredith and welcome from the other coast.


I've read a bit on the straw bale house, one of the articles was about moisture infiltration, retention and mildew or mould or both (don't recall which) but it was about testing existing straw bale houses.

The basic results were any place that had high humidity, frequent rain + high wind (horizontal rain) generally mild winters with a frequent freeze/thaw winter tested poorly and were not recommended. The combination of those weather conditions are tough on stucco as well which is probably part of the problem. South West Nova Scotia were I live was named as one of the places not recommended for straw bale. 

Being in the early planning stages is the best time to consider the construction type and exterior finishes that best suit you location and intended use then work your way in to the rest of the building to support it.

Note the above thoughts are just info to consider, I did not want it to sound like I was against straw bale.


MatthewMeredith

Quote from: Hilltop366 on July 24, 2018, 05:37:15 PM
Hi MatthewMeredith and welcome from the other coast.


I've read a bit on the straw bale house, one of the articles was about moisture infiltration, retention and mildew or mould or both (don't recall which) but it was about testing existing straw bale houses.

The basic results were any place that had high humidity, frequent rain + high wind (horizontal rain) generally mild winters with a frequent freeze/thaw winter tested poorly and were not recommended. The combination of those weather conditions are tough on stucco as well which is probably part of the problem. South West Nova Scotia were I live was named as one of the places not recommended for straw bale.

Being in the early planning stages is the best time to consider the construction type and exterior finishes that best suit you location and intended use then work your way in to the rest of the building to support it.

Note the above thoughts are just info to consider, I did not want it to sound like I was against straw bale.
Thanks for the feedback, Hilltop! I've read those things about straw bale as well, and moisture is definitely high on my list of concerns. However, I'm planning on only doing a single layer of plaster (for fire protection), then a 1x2 rainscreen, then a mix of corrugated aluminium siding on high exposure walls and cedar shakes on more protected walls. The idea is that it will still have all the benefits of straw bale infill (which I am VERY keen on) while being better protected from moisture than relying entirely on plaster.

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