Goal: Timber framed wattle and daub house. Help!

Hello all,

Beginner natural builder here with some questions about a design I'd like to make reality. I built a few small two-room timber framed wattle and daub houses a few years back, have several years of basic carpentry experience, and would like to build my own home with this technique. I'm about 18-24 months out from the build and I'm posing questions now so I have plenty of time to work out the kinks so things hopefully end up at least in the same ballpark as "according to plan", with no major failures due to a lack of foresight. I'll start by explaining a bit of how I'm thinking this will look, then I'll pose a few hopefully-easy-to-answer questions (i.e - "that could potentially work, but we need more info first", "absolutely not, you're heading for disaster", or something like that).

Sorry in advance for switching between metric and imperial measuring systems. I live in Central America and I'm stuck between both. I have to fill up my car with several liters of gas and drive a few kilometers down the road to buy a quart of oil to make sure my engine doesn't seize up on my way to the market to buy couple pounds of potatoes. All that to say, lumber is measured using the imperial system and not metric. Also important to note, the only lumber I have access to where I'm at is ocote pine. I'm no expert, but I've heard ocote compared to eastern white pine.

I've attached two images that show the basic layout of the house I'd like to build. Not every single measurement is included, just broad strokes. I'd like space to be divided into 3m x 3m x 3m blocks (interior space), so 10ft x10ft rooms with 10ft ceilings. I have limited horizontal space to work with, so I would really like to be able to build up safely and not have to build out. The red squares in the images represent where load-bearing posts will be anchored to the foundation. The interior bathroom wall is not load-bearing and I'd like to just use 2x4s if possible. The same goes for the wall/windows in front of the stairs on the second floor. The second floor wall/windows just mentioned is the only wall on the second floor that will not stand on top of a first floor wall. I only put it there because it's not load bearing and will not be filled in with earth like all other walls, I'll probably just put up plywood or drywall here (I'm open to suggestions for lightweight, natural alternatives). It's probably important to not that the space on the second floor directly above the living/dining room will be a balcony/deck thing with the walls to the left (let's say East) and North only being about 1m tall. The walls in the images are 30cm/12in thick. I have in mind to use an 8inx8in post if dimensional lumber or 8in diameter if roundwood, with 2in on either side for wattle, daub, and lime plaster finish. It would be nice to be able to buy mostly 25ft posts, assemble beams and braces on the ground, cut off the excess at the top and raise it up.

Now, a few questions:
- I live in an area with moderate seismic activity and wind conditions, is it too risky to go for a two story building or can I make it work?
- If I can make a two story building work, then what dimensions would you suggest my posts and beams be? Could I get away with 6in x 6in / 6in diameter?
- Can pine beams span 3m / 10ft safely with only a window framed in 2x and a few other 2x to attach wattle to?
- Can I get away with bigger windows?
- What are red flags that stand out to you based on what I've shared?

I'd be truly grateful for any insights anybody could share with me. I certainly don't expect to hit the bullseye with most of an idea and a very rough draft, so please don't hesitate to tear apart my plan if I'm not heading towards success. Thank you in advance to anyone who takes the time to respond to this. I've gotten so much out of these forums and I hope to one day be able to give back once I have the knowledge and experience to be of some use to others.

I have a lot of experience with what you are doing, except for the 'shaking', Australia generally has no issue with them.
I do know from other experience there is a need to ensure a building does just not drop to the ground, crushing people.
There are techniques for that which include concrete bond beams.
Have you considered adobe infill panels between the post and beam structure?

Hi Shea,

Are you in tropical climate or highland tropical?
Why do you want to build with wood if standard is masonry in Central/Southern America?

Hi Cristobal,

I am in a tropical climate (I'm floating between zone 12a and 12b). I decided on wood because I've made wattle and daub houses using the bajareque/bahareque method before, so it's familiar territory. I would have used adobe bricks and concrete bond beams on each floor, but I'm still a little hesitant when it comes to seismic resistance. I've seen two story adobe buildings while living in Perú (much more seismically active than where I'm at now), but I've seen that both succeed magnificently and fail tragically. I wouldn't want to risk the latter. The only other masonry options I have here are concrete blocks, which are off the table for obvious reasons and fired bricks. I could use bricks and lime mortar, but I wouldn't get the same thermal isolation outcomes that I would with adobe or bajareque/bahareque walls. The brick option would also require concrete posts and beams which makes the build very expensive, very fast. In a perfect world, I would go with 30cm x 30cm adobe bricks, concrete bond beams, and a dutch gable roof to top it off. If anyone here with experience with two-story adobe brick construction could sign off on the viability of this idea, then I'd gladly save the trees, bamboo, and go with adobes.

Hi John,

The idea would be to erect 20ft approx. posts with beams and braces at ~10ft and ~20ft to fasten floor and ceiling joists to, ideally eliminating the risk of a wall collapse. As for adobe infill panels, that is what I have in mind. I would mount a standard 2x stick panel and fasten 1" diameter bamboo shoots at 10" intervals up the wall, then fill with adobe mix (clay, sand, dried pine needles). You mentioned bond beams, which I talked about in my reply to Cristobal. I'd love your take on what I mentioned to him about using adobe bricks rather than a timber frame and adobe panel infill. One of my concerns with a two story adobe construction that I didn't mention in my reply to Cristobal would be that the second story deck area would make the second story wall layout non-rectangular (it would be L shaped) and potentially compromise the building during a strong earthquake. Maybe I'm wrong about this, I'm certainly no expert. What are your thoughts on this? If I can go with adobe bricks and scrap the timber frame idea, then I would save trees, time, and lots of money.

Shea,

If you went with adobe I would definitely stick to one floor building.

Factors that lower earthquake dangers: rectangular/square floor plan, slab foundation, thick walls, bond beams, smaller openings and never by the corners, buttresses on long walls (or structural walls perpendicular to the main wall), vertical reinforcing, horizontal reinforcing.

I doubt that 30 cm walls made of adobe without any reinforcing in the walls would have sufficient shear strength, unless the building is very small. Mine are CEB 60 cm exterior and 40 cm interior, all with bond beam, which creates lattice over entire structure.
I also have vertical reinforcing (12 mm rebar through the holes in the blocks and grouted) every 80 cm. For horizontal reinforcing galvanized ladder mesh every 3 courses (30 cm). The house was approved by engineer and is in low seismicity area.

I don't like concrete blocks, but I think that in rainy seismic tropics I would choose them over adobe.

The best would be to have access to structural bricks (ladrillo estructural). I consider them the best building material. I don't know which country you are in, but I know they are manufactured in Mexico and in Colombia.

From; https://www.world-housing.net/wp-content/uploads/2011/06/Adobe_Tutorial.pdf
• Build only one story high.
• Use an insulated lightweight roof instead of a heavy compacted earth roof.
• Select a wall layout that provides mutual support by cross walls and intersecting walls at regular intervals in both directions (alternatively, buttresses can
be used).
• Keep openings in the walls small, centered, and well-spaced.
• Build on a firm foundation. Walls are the main load-bearing elements in adobe buildings.
A number of empirical recommendations regarding earthquake-resistant wall
construction are as follows (Figure 3.11):
• The wall thickness should be at least 400 mm.
• The wall height should not exceed 6 times the wall thickness at its base, and in any case should not be greater than 3.5 m.
• The unsupported length of a wall between cross walls should not exceed 10 times the wall thickness, with a maximum of 7.0 m.
• The length of wall openings should not exceed one-third of the total wall length.
• The length of openings should not exceed 1.2 m.
• The length of piers between openings and the distance from cross-walls to openings should be at least 1.2 m.

Other points in that article include;
- Plastering the walls adds strength
- reinforcement of ring beam must be continuous
- bamboo or cane can be installed inside the wall as a grid, fastened at each crossover
- Buttresses at openings help a lot.

This reference is a huge tome.
It is worth reading.
making-adobe-earthquake-resistant/

Hello all,

I really want to stress how grateful I am for the time each of you has taken to reply to this post. Your insights are very much appreciated. Although adobe building isn't off the table for me, I'd really prefer to stick to the wattle and daub style mentioned in the name of the post. In Central and South America the style is often referred to as bajareque, bahareque or quincha. I am certain that two story buildings are possible and safe using this building style, I'm just not sure of the dimensions of the lumber and spacing, thus the questions I asked in the initial post. I have some manuals that the Colombian and Peruvian governments have published with their safety standards for this building style, but they are using guadua bamboo. I can probably get my hands on this in the quantities I'd need, but would prefer to not have to buy all the inputs necessary to treat the shoots for repelling pests, not to mention it's just a lot easier to work with dimensional lumber. Any knowledge anyone can share with me regarding lumber dimensions for posts and wall panels, spans for joists, etc. as it relates to wattle and daub would be very helpful.

As you say your ocote pine is supposed to be comparable to eastern white pine, I can put in some information for you. I have a 131 year old barn in upstate New York, built with either white pine or hemlock or both, can't always tell from exterior appearance. It is 32'x 42', with 8 x 10 main posts and beams, bents of 16' spans at 15', 15', and 12' spacing. I would say your plan of 8 x 8 posts at 10' spacing each way would be fully capable of standing for a century as long as it is protected from weather. I would make sure to include diagonal bracing to resist possible seismic activity. 6 x 6 posts would be strong enough in my area, but with seismic loading I don't know.

Sticking with the bamboo because its interesting, it appears to be a great bamboo for building.
https://www.guaduabamboo.com/