Cumaru is less stable than ipe. I sided a house with T&G ipe a few years ago. Install included removal of existing black board and cedar channel,1/2'' plywood,ipe with con adhesive ss screwed thru the T, twp finish. Man that thing has a glow in the sunset. I took the Harley up there last week just to see how it was going the new owner was happy to see me and we had a walk around. Still looks the same after hmmmmm 5 years or so.
J.

ipe is currently out of my price range, i ruled out cumaru as from what i hear it moves too much in dry climate. so i am thinking massaranduba or garapa (both under $2 for lf). garapa is too light for the contrast i want to achieve with light grey colored hardi boards. i will take my garapa sample to local stain shop see if they can suggest something to darken it. my worst fear it that any hardwood is going to warp too much once i put it up. but than, maybe i worry too much. you can check out what i am doing on link below.

Here is a link that might be useful: my house

I have installed a wide variety of rainscreens including Ipe and Cumaru and we install and distibute a raincreen system that works very well.

Check out the link to see some completed projects with the rainscreen system.

Regarding the use of decking, I would not recommend using decking for the rainscreen for the following reasons:

1. If you want concealed fastening, you will need to have pregrooved or pockets in the top edge of the board to receive the clips. The pocket can hold water which could freeze in the winter and cause the board to crack.

2. Most of the boards will be crowned and it will be very difficult to get consistant reveals. The use of a modified bow wrench can help, but it won't look perfect.

3. There is not a drip point on the boards which will result in uneven weathering if the material is to be left un-oiled.

4. Be very careful if you want to have mitered corners. They will open up on you and a rainscreen system like ours that allows the boards to float will result in better looking miters. The taller the board is, the more dimensionally unstable it is. Thus, 1x4 looks the best with mitered corners, then 1x6. I would not recommend mitering any 1x material taller than 1x6 without increasing the thickness of the material--which will increase the material cost dramatically as 2x hardwood $$$.

I would not recommend face fastening the boards as this will restrict the movement and contribute to cupping in the boards. Also, you will get streaking along the lines of the fasteners over time as the wood weathers. 304 Stainless Steel is a must if you choose exposed fasteners and again, don't miter corners. For your design it would look better if you cut the end square and alternate which board extends to the corner.

Hope that helps. Feel free to email me for more info. It looks like a great project. I have also installed HD Fibercement and am currently isntalling 4000 sq ft of hardi-panel on a house if you need info on that portion of the project.

Jon Stephen
Green Facade Systems
ph. 773-931-4517
email: specialtyexteriors@gmail.com

Here is a link that might be useful: green facade systems photo gallery

Great Span Job Joe!!! and welcome a board. J.

1. i will not have hidden fasteners as i have open joint. will countersunk screw.
2. this is my biggest thing i am worrying about. i am trying to find local distributor so i can return anything that is not straight.
3. i will oil
4. i want to miter. i will not attach together mitered ends at the corners.
also by 1x do you refer to really to 3/4"? i received samples of hardwood that were both 1" and 3/4" both referred as 1x.

You might have a local in Coloardo

but if so the lumber has been thru several venders so the price is going to be up there. Do not expect any lumber to be prefect,learn to work with the wood.

Defentley do fasten the miter corners. Usually 5/4 is 1'' thick 3/4'' is called out as 1x, dont even ask why. J.

i went to closest lumber yard today, they had lf of 1x6 cumaru for astronomical $3.75, i didnt even bother to negotiate, just turned around on my heel and left. i just waoory i will receive a lot of bent pieces and have hard time returning it for replacement.

I see your house plan and understand its your first house. The learning curve is usually sharp for the first one.

And I like the way you spell it makes me look really good!!!

In any stack of lumber you buy there is going to be a few " bent " pieces thats the nature of the game. Now if you make it clear to your vender that you want Perfect material at the get go Im sure the two of you can work up a price that will allow you to pick thru his inventory. That price is going to be a little high. J.

J, do you mean aur haus? heh, our house was not available so i had to pick alternate, hehe. i am not born american either so it doesnt look that bad to me. anyway, thanks for all your advices.

I am planning to install a similar rainscreen siding systme with open joints but am concerned that it will become a hotel for wasps and other insects. Can anyone who has experience with this system comment on this? Thanks