Brian Rader

Hi all,
I am having some mold problems on roundwood timber I am hoping you might be able to help with.

Building is an octagonal structure, using roundwood timbers for the posts, beams, and rafters. We are located in the maritime Pacific Northwest. When I initially cut down the trees for this project, it was late spring. Soon after cutting them down, I used a draw knife to strip the bark, then left them in a part sun-part shade area to dry out sitting on some alder logs (as stickers). They were not rained on. In late summer we started seeing some black moldy growth on many of the logs (again... no rain). We washed all the logs with soap & water. They continued to get moldy. We tried treating them with white vinegar/water mixture & it did not seem to help. The only timbers that did not mold were ones where I stripped the bark later (brutal process where the bark & underlying wood had fused strongly together making the draw knife work very, very difficult; wood after stripping is very dry). The timbers that did mold were the ones that I stripped right away (draw knife more easily gets under the bark, exposing a very slick wood surface). Wood is doug fir & hemlock.

Any ideas on what I can do to prevent this from happening in the first place?
Any ideas on how best to 'treat' the ones that did mold?

Thanks in advance for your time & help. Much appreciated.

Closeup of siding & windows.  

Cedar shake siding & rescued craftsman windows.

Next, a close up of the moss roof & the cupola!

Thanks again for all the help & responses to this.  Making progress & thought I should share some pictures.  First, cupola & moss roof... view from the ground!

Thanks you guys for the thoughts & ideas. I appreciate you taking the time to reply!

Jay: Thanks for the big welcome (long time reader, first time poster)! I think you got the essence of the roofer's comment... very, very difficult to make 8 seams watertight with metal on this kind of structure. He described a previous experience with a similar structure as one of the more difficult & frustrating building projects he had taken on. And, I am no professional! Thanks also for your thoughts on latex & "living" roofs. It is unlikely that I will get a PE to do load calcs. Going to have to try & keep it as light as possible to stay on the safe side. Actually, we had been reading about Jack's moss idea & are intrigued by that...

Jack: Thanks for the moss idea & vinyl link. I need to do some more research on this. Interested in the lighter weight of of moss roof, but still get the "living" look. Need to understand if vinyl would hold up. Need to figure out if some kind of substrate ("soil") would still be needed. Need to understand if root barrier and/or drainage is needed. I have a nice healthy crop of moss growing in my yard right now! I read somewhere that you can put moss in a blender with yogurt & then paint it on! Need to learn more before spring!

Alder: I like the cardboard/carpet/cement idea, too! Kind of takes me back to latex-concrete, w/o the latex (& maybe w/o the concrete!). Like in my reply to Jack, could be that a fairly lightweight carpet might be a good substrate for the moss. Great ideas!

I am also thinking that this building needs some kind of cupula! Would like to show off the wagon wheel around the center pole & let some light in. May also try to incorporate some ventilation. Building is likely going to be a combination barn & chicken coop, but you never know!

Thanks again ! ! !

Brian.

3rd picture. This one shows the cedar centerpole where the hip and mid rafters are attached.

One picture worked, where three did not. Here is a second picture!

Hi All,
I am hoping to cull the collective knowledge base here for some ideas on roofing an octagonal, roundwood-framed barn/out-building. The building uses a beefy (~18") cedar trunk as a centerpole. The roof pitch came out to be about 2.8 in 12. We had planned on a 3+ in 12 pitch but circumstances conspired against us & we ended up with a bit shallower pitch, limiting our options somewhat.

Really don't want to use asphalt shingles (from a financial & aesthetic perspective). Thought about metal (actually have some around that might work), but was STRONGLY caution against this by a builder we trust (said wind blown rain will keep the hip rafters wet & rot them). Thought about the velacreations latex concrete roof (even bought the Knott/Nez book: 'Latex Concrete Habitat'). When I calculated the amount of latex & the cost, however, decided to look for other alternatives. Latex is expensive & there is very little info about this approach online. Thought about cedar shingles. We live on an island in the PNW & there is a lot of cedar available. However, most resources suggest a pitch of at least 3 in 12.

This leads me to looking at a living roof or a simpler (?), lighter weight (?) moss roof. This is not an engineered structure. This has been and will continue to be true design-build (and not all of it that well thought out at times as I am learning as I go). I have no idea what kinds of loads my round wood framing can take. Plan would be to sheet the roof using boards or plywood, add EPDM (or similar, ideas encouraged), add media & some kind of drainage, then add moss/sedums/other. We are looking for simple, inexpensive, using as little purchased/manufactured product as possible. We are very puzzled by drainage issues & media/substrate. Any thoughts & ideas are appreciated. Right now all we have is the framed structure (tarped for the winter to minimize damage). We are open to possibilities & constantly limited by imagination! I will try to attach some pictures... I hope this works! Note for the pictures: each of the 8 pie shapes in the roof consist of 2 hip rafters (these go directly over the 8 outer posts to the cedar centerpost), 1 mid-rafter (these go from the centerpost to the mid-point of the beam (half way between each outer post)), and 2 jack-rafters (these attach to each of the hip rafters and span the distance between the hip rafter and the mid-rafter). With the addition of the jack rafters (not shown in the pix), the maximum distance between rafters is a bit over 2-feet at the bottom of the slope.

Here are some pictures. Thanks in advance for any ideas!!!
(tried to post 3 pix, but no luck. Trying again with one...)