Wooden posts as stilts

[cwhaley]

I'll be putting up a summer house with small balcony next year. I've contacted the local authority with my plans and there are no restrictions. Both neighbours have no problem with the plans either.

My query though is about the stilts I intend the fix the summer house and decking onto, rather than a concrete base. I've never used timber as a structural base in this way before -- a shed I have is sat on railway sleepers on slabs and a small brick storage shed I have is built on brick foundations.

My plan is to mark the locations for the posts/stilts, dig around two and a half ft down, put a treated timber post into this hole and level. Afterwards pour a dry concrete mix into the hole, compact it and then add water. I would have the concrete a couple of inches above the surface of the ground so nothing pooled there.

Would this be okay? The posts would be underneath the summer house and decking so protected from direct rain -- it's just the moisture elsewhere I'm concerned about. Maybe there's nothing else to consider and I'm over-thinking.

 

[HERTS P&D]

Use a concrete spur concreted into the ground and then bolt the post to it. Use bolts completely through the spur and post.

Andy

 

[JohnD]

wooden posts in contact with the ground will rot

There are a few alternatives:

Concrete spurs, with the posts bolted to them, 6" above ground level to avoid rainsplash

Steel sockets set in concrete or bolted down, incorporating a drained or raised gripper or platform

You can put formwork round the top so when your pour the concrete, all that will be visible above ground is a neat small square (or circle). If using the steel sockets, paint them well before casting or bolting them.

Use stainless bolts (or studding), washers and nuts. Studding is cheaper in large sizes and you can buy it cut to size.

Soak the top and bottom of your posts in preservative overnight anyway.

You can paint the concrete with masonry paint to help it blend in (I use "bitter chocolate" colour to match the woodstain)

edit
too slow

 

[cwhaley]

Thanks for that just watched the clip.

I've seen it before on public fences but it didn't cross my mind for this project; just need to look at sourcing the concrete posts locally. Sounds like a better plan as it would mean the timber is kept entirely off the ground.

 

[cwhaley]

wooden posts in contact with the ground will rot

There are a few alternatives:

Concrete spurs, with the posts bolted to them, 6" above ground level to avoid rainsplash

Steel sockets set in concrete

You can put formwork round the top so when your pour the concrete, all that will be visible above ground is a neat small square (or circle). If using the steel sockets, paint them well before casting or bolting them.

Use stainless bolts and nuts.

Soak the top and bottom of your posts in preservative overnight anyway.

Thank you for the pointers they are helpful. There will be lots of airflow underneath the summer house anyway as it'll be up to a foot off the gound to stop rats and foxes nesting there as has happened before.

I put up a couple of small wooden posts elsewhere in the garden and capped them with a moulded steel sheet so will probably do the same with the timbers.

 

[HERTS P&D]

Is there a branch near you?

http://www.builderdepot.co.uk/1200m...MIzaSyoY6k3QIV7bvtCh0KbwTcEAMYASAAEgINi_D_BwE

Andy

 

[cwhaley]

Is there a branch near you?

http://www.builderdepot.co.uk/1200m...MIzaSyoY6k3QIV7bvtCh0KbwTcEAMYASAAEgINi_D_BwE

Andy

I've seen some really good deals with them before for other products online but sadly the nearest branch is about 130 miles away (they only seem to be in London?).

 

[HERTS P&D]

OK

https://www.google.co.uk/search?rlz....0...1c.1.64.psy-ab..4.1.162....0.iEBv9cdc_cs

Phone around

Andy

 

[freddiemercurystwin]

Or just use one of these in between the top of your foundation and the post. https://www.toolstation.com/shop/p2...MIju6fppCk3QIVSLHtCh1c_QNNEAQYASABEgI1k_D_BwE

 

[^woody^]

The telephone poles in the ground around me are still upright after at least 60 years. I think they are Douglas Fir, a softwood.

Just sayin

 

[JohnD]

old telephone poles were treated with full-cell hot creosote (vacuum plus pressure). You might notice they bleed tarry stuff out of cracks in hot weather. Old railway sleepers the same.

You can't do that yourself.

 

[bernardgreen]

An alternative is to create pad foundations and stand the posts on a piece of 4 mm thick sheet lead. The post is not fixed to the pad in any way other than by the weight of the summer house. Two coats of Sadolin Classic protects the sides of the post and the lead presses into the end grain to seal it from moisture ingress. The lead should be trimmed to the same size as the post to prevent water pooling on the tip of the lead.

Any movement of the post caused by shrinkage of the timber frame is allowed for by the the post not being rigidly fixed to the foundation.

This is one we did in 1980, the ends of the posts are still in perfect condition. ( lead was trimmed after the photo was taken )

 

[^woody^]

You can't do that yourself.

Pressure infusion is just an economical industrial process to save time. Creosote is still available

Soaking timber in creosote will give the same effect, just a few days longer to do.

 

[JohnD]

Soaking timber in creosote will give the same effect, just a few days longer to do.

It won't give full-cell treatment.

But it will cause dangerous soil and water pollution.

 

[^woody^]

It won't give full-cell treatment.

But it will cause dangerous soil and water pollution.

Borates!

Of course it will. The preservative gets absorbed into the errr, cells. Fully.