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Installing Vigas in Adobe

CloudHidden's picture

Some of you here are into adobe architecture. Anyone have info on installing vigas in an adobe wall, and also in framed walls. What are the waterproofing methods? What type of wood is used for a viga?


(post #92612, reply #1 of 4)

I worked in Taos thirty some years ago for a year. my memory is a little shaky on this but as I remember, you just laid the Vegas across the wall and mudded in and around them. Since they protrude for a large overhang, and the roof deck is above them, there is little chance of water geting back in there. Drying out and shrinking was the greater problem but with true adobe, you are replastering every so often anyway. And a dessert is not a place where you aften find days of rain to eroded and seep in around the ones that are exposed.

For those who are wondering, a Vega is the large round tree trunk that acts as roof and ceiling joist in flat roofed adobe structures in the desrt southwest. Sometimes it protrudes through a parrapet wall in the front of the structure.


Excellence is its own reward!



Oh Well,

We did the best we could...

(post #92612, reply #2 of 4)


Haven't been around as often as I should.  I've been pretty whipped lately.  Hot sun, body grinders and spray gun.  We always knock the fuzz off our rough-sawn.  Not enough to get rid of the saw marks...just clean them up a little.

You have a bond beam.  Either wood or concrete.  Vigas on top.  If wood, mongo lag screws to reduce twisting, if concrete anchor bolts. Not required by code, but you don't want that green wood to twist any more than it has to.   Then infill with more adobes up to the decking level.  We always cut ours off outside in the interest of maintenance....but a cap of sheet copper can look cool and protect from the sun.

For frame walls, we build a pony wall on top of the normal one and slide the viga into the pocket.  Here that also requires anchoring even tho the pocket is small enough to prevent movement.

Inside linseed oil and turp (not mineral spirits)  makes a fine sealer.  50-50.  Outside is fine too if you don't mind redoing it frequently since it's got no UV protection.  But here's a recipe from our only honest-to-gawd, second-generation paint store.  Very cool people.  Based upon BM products but you can change it if you prefer another brand.

3 parts linseed oil:  1 part turp:  1 part ArmorAll Water Repellent:  1 part BM Deck and Siding Stain Clear #07600:  1 part BM Moorwood Solid Color Oil Stain (optional for color)  These products have solvents to drive them into the wood and provide UV protection.  The solid color is such a small percentage that it doesn't obscure the grain....just tones down the wood somewhat.  Very cost effective and a lovely mix.  My hands may be sore, but my cuticles are in great shape :o)


(post #92612, reply #3 of 4)

Pine.....because that's all we have.  Anything would work, I suppose.  Can do a round viga or square beam of varying sizes.  Depends upon how formal the style and your taste are.  If you do square, an ogee or a bead down the two edges is a nice subtle touch that doesn't take much time.

Spacing depends upon whether they're structural or just decorative.....tho the traditional look is 28"-36" OC since in the old days they were structural.  You can go up to 48" OC and still look good if just decorative.  Gotta go, sun is rising.


(post #92612, reply #4 of 4)

Thank you Shelley!