Help with choosing timber gazebo

boots_babe

Hi,

We are having an extension built, the architect's plans include a timber framed gazebo that will be next to the house, and house a new outdoor kitchen.

On getting builder quotes, some are including the gazebo and some not. One builder gave a price of £13k for oak and £8k for larch. So I have been reading into types of wood, and have seen quite conflicting advice. Lots saying pressure treated larch lasts 10 years at it's only rated as Class 3 (moderately durable) versus oak which is Class 2 (durable) and lasts 25+ years. But then other online information says larch can last up to 50 years if well treated.

So first part of my question is, does anyone have any experience of each option and can share their views?

Second part of my question, is that I'd like to cost up having a gazebo made separately to the builder, just to see if it works out cheaper or not. There are so many sites online that offer this, it's hard to know who is actually reputable and good quality. Can anyone recommend any that they have used?

Many thanks.

casper_gutman

I've seen the expected life quoted as "10-15 years" for class 3/moderately durable and "15-25 years" for class 2/durable timber species. So the figures you quote seem to be the best case for oak and the worst case for larch.

I'm slightly surprised you mention 'pressure treated larch' as often larch is used untreated in place of less durable softwoods that have been treated. I'd expect any old pressure treated pine to last 15-20 years outdoors above ground, and even untreated larch should match that, so the figures you have seem pretty pessimistic.

Whilst the official lifespan for larch may be ~15 years, there are plenty of articles suggesting it will often be good for much longer, as long as it's not in contact with the ground. This page Larch Timber | Douglas | larch woodTuin Blog (ok, it's from someone trying to sell you a larch gazebo, but it's a site with a pretty decent reputation for the quality of the products and of the advice offered) suggests larch should last 5 – 15 years even in contact with the ground, and if it's not in ground contact then 50-60 years when untreated or 100 years if treated and used above ground outdoors.

Personally, I'm a relatively young 40-something, and if I invested in a pressure treated larch gazebo I would be hoping it would outlast me.

boots_babe

Thanks so much for such a detailed reply. I've seen lots of information saying that the lifespan is higher if not on the ground, but as a gazebo it will have ground contact so I've assumed this doesn't apply for what we need.

I've seen lots of links like the one you've posted, it's just it's hard to know what is true as the information on different sites does seem to vary a bit. I just don't want to take a false economy by choosing larch, then finding in 10 or so years it all needs replacing.

Early 40s here too and definitely want something to last for decades rather than just years!

FreeBear

boots_babe said:

Thanks so much for such a detailed reply. I've seen lots of information saying that the lifespan is higher if not on the ground, but as a gazebo it will have ground contact so I've assumed this doesn't apply for what we need.

Steel post supports will keep the timber off the ground. Admittedly, some of them can look pretty ugly. Have seen custom made stainless steels supports that look much better. A local S/S fabricator could probably knock a set out at a not too expensive price.

Something like this perhaps - https://www.canopyproducts.co.uk/shop/stainless-steel-t-shaped-fin-post-base/

weeg

Have a look at the timber decking and cladding association website. There's some good info on different durabilites. 

Steel post supports are definitely a good idea. Simpson strong tie have various ones.

Rdwill

Mine has got oak legs, and a softwood top.

The legs have probably been there 25 years and are as solid as the day they were put in.

When I moved in the top was pretty ropey, but I replaced it by using what was there as a template.

To replace the top cost less than £100 and a couple of days of my labour. I'm glad I didn't have to replace the legs as that would have been a pain.