Thread: Water proofing hardwood post

Okay guys, there seems to be a couple of points around this that we disagree on. I figure we all have differing experiences that have shaped our opinions hence the disagreement. So I'm going to share my thoughts on these things and why, and hopefully you'll share yours, and even if we can't agree we can at least learn why we think different.

I see no issue with using logs in the round so far as structural failure goes. Over the years I've sold a lot of logs into pole homes and am yet to see one fail. Logs are not like big sawn sections, the internal stresses are in stasis, and while they may shrink a little with drying that actually makes them stronger as they pull onto any internal faults. Walk outside and go look at some power poles... They were dead green on installation too. Big sawn sections blow out because the internal stress equilibrium is out of balance due to uneven removal of wood during sawing.

With regard rot I'd split the issue into two parts- sapwood and heartwood.
Sapwood is rot prone. Were it me I'd have either pressure treated that post, or removed the sapwood. (Removal of all the sapwood in total has no effect on the stress balance of the round log because the stresses remain evenly balanced). At this point its a big job given the post is installed so I'd now be either looking at a remedial treatment like copper napthenate in situ, or letting it rot off with a bit of help from a chisel.
So far as the heartwood goes, this is a class 1 in ground timber. And its one of the more rot resistant species in that class. It'll rot - eventually. But you could use steel and it would rust eventually too. I'd put my money on the bloodwood untreated to outlast either gal plated steel or treated pine in that application any day.
Regarding condensation etc etc.... This was my home for 6 years and she had a few decades on me.... The other great love of my life.
With sensible precaution and good building practice condensate issues are non issues. You know its going to be an issue you allow for it right?

So that's my $0.02. I hope y'all will share your experiences that lead you to think differently

Originally Posted by John.G

Regarding condensation etc etc.... This was my home for 6 years and she had a few decades on me....

Well I'm unsurprised you moved out John. Milling timber there must have been a bloody nightmare.

I stake what I have said on 52 years in the building industry and experience. If what John G advocates and it works, your in front, if it don't, your time, your money, your headache, your choice. having said that, if ever you sell the property and the buyer is savvy, the buyer will get an independent pre purchase building inspection and don't be surprised if it doesn't raise some serious doubts which could have an adverse affect on the sale. I do take on board the implied message of john G's photo.

I'm happy to expose myself for what I am. Unqualified. However, I do have a good depth of experience in construction both residential and commercial. Currently I am building a free standing structure 16 metres wide and a bit over 45 meters long, 2 100mm steps in the long length.About 4.6 metres high.

I also have good experience with waterproofing along with good knowledge of the code. I have on numerous occasions had to repair / make good substandard work performed by others. Often it is a nightmare, and very, very costly. I work from plans and specs provided by engineers via builders. I am generally one of the first on site, often setting profiles for the building set out. Framing, cladding, windows and doors, roofing, rainwater goods, mezzanine floors (including frame and sheeting) are all part of my skill set.

I appreciate what JohnG says, and yeah, it might work. But, my main concern would be the intersection of post to floor and how you ensure that moisture does not get into the sub frame where damage would occur slowly, over time, and would be awful expensive to repair at that point.

If a code friendly solution to that problem can be found for that, then go for it. Document it, then on sale any nay sayers / inspectors can have their concerns addressed. But like RW build says you will have those dudes, and the potential buyers to convince. Some may be harder to convince than others.

Nice idea, execution needs work, in my view.

Cheers

Bit of luff in those sails John!
What hasnt been discussed is the difference between wet rot and dry rot.
Upon first seeing the pic of the shower my alarm bell went off.
I respect Johns points made and the fact it is Bloodwood - a very durable timber to wet rot. But in an application such as this, dry rot can be somewhat more sinister.
Using boats as an example; while in the water, things are going along swishingly. Once out, nasty things start to happen.
For me, I'd be keeping structural exposed timber well away from a shower. If timber is required for aesthetics, make it easy access and easy removal.

My view is that we shouldn't be focusing on the Bloodwood post.
It can probably be given a coat or two of a suitable epoxy, or even left untreated and it'll outlast the rest of the house.
My concerns is protecting the timber in the wall framing and floor. I can't see how the shower can be properly waterproofed without covering the post with the waterproof membrane. which sort of defeats the purpose of having exposed timber in the shower in the first place

There is a proper process to water proof a shower. This shower is a little unusual in that a post is exposed at the corner. But the process of doing it properly remains the same. There is an Australian standard AS3740 for waterproofing of domestic wet areas which should be complied with on a new bathroom build. In essence, they require that:

• In the shower, the whole floor must be waterproof and the shower walls should be waterproofed up to 1800mm.
• The walls need to be waterproofed up to 150mm.
• If the bathroom floor is made of or contains wood or if the bathroom is on the second story or higher, the whole floor must be waterproofed.
• Over the step down to the floor should be waterproofed to 100mm.

Looking at your photo posted:
shower.jpg
I could see the tiles already laid and it looks like some sort of grouting is applied at the base of the post. The issues you are facing with

1. Waterproofing should be done before tiles are laid, water proofing should form a continuous membrane enclosure for the whole shower including the walls, floor and the step down. The post should be treated like a wall with external and internal corners.
2. Are the wall made of cement sheets or plasterboards which I believe are a not suitable shower wall material.

The process of water proofing involved reinforcing all corners and openings with fabric tape or special formed corners and sleeves, together with water proofing compound forming a water proofed membrane. Look at the Bunnings video:


Withe the proper process, the post would be outside of the water proved barrier and shouldn't be your sole focus. If you get the process right, the post would take care of itself.
I suggest that you rip up the tiles and start the water proofing from the beginning.

Remove timber, waterproof shower, reinstall timber.

Simple. easy.
Removes all chances of moisture getting through to framing timbers.

Or am I missing something?

Originally Posted by chris0375

Remove timber, waterproof shower, reinstall timber.

Simple. easy.
Removes all chances of moisture getting through to framing timbers.

Or am I missing something?

the timber post is part of the structure holding up the roof and supporting the walls

Originally Posted by ian

the timber post is part of the structure holding up the roof and supporting the walls

Well that complicates things!