Piling and Insulated Foundation - combination possible?

[AppleDown]

Hi everyone. I've been posting about the design we have for our self build, and one of the biggest limiting factors we're coming up against is an oak tree in a conservation area. It's a big boy - no TPO - but would no doubt receive one if we made an enquiry to remove, which we wouldn't want to do anyway.

 

The question I have is regarding a mix of foundation types. One of the proposed ways to build closer to the oak is piling based on a radar scan for where the roots are, and do a raised foundation to allow water/air etc underneath (believe it's 2.5cm, but may be wrong). But as this is just in one small corner area of the house, is it possible to have that as a piled foundation, and then the rest as an insulated slab? I'm assuming it should be ok, but then need to take into account that particular corner of the house will be less energy efficient than the rest. Any thoughts/info appreciated. Thanks!

[Big Jimbo]

I doubt that an engineer is going to allow you to mix foundation types im afraid.

[George]

If you pay for the ground investigation, site prep, pile rig to get to site, set up and do some piles, the extra cost to do more piles is not great. 

 

You should be able to make a pile supported raft slightly more efficient than a normal raft, too. Overall it'll cost more but shouldn't be dramatic, especially per sqm if you are able to make it bigger. 

[ToughButterCup]

The set up cost for our piles was about £5000. The additional cost of (unplanned - 'where we might want to put a garage'  ) piles  was £50 each. We threw in a couple of others between our piggery and the house for when the piggery is extended 'into' the house 

 

Have a read of my stuff about piling. Overall cost for 146 sq m was £6500.

[The Reverend]

Piles and a ground ring beam maybe?

Tree protection zone is 12 x diameter of tree at chest height

[AppleDown]

1 hour ago, ToughButterCup said:

The set up cost for our piles was about £5000. The additional cost of (unplanned - 'where we might want to put a garage'  ) piles  was £50 each. We threw in a couple of others between our piggery and the house for when the piggery is extended 'into' the house 

 

Have a read of my stuff about piling. Overall cost for 146 sq m was £6500.

Thanks for the info - and just read through your blog posts. Lots of research coming my way then. When you say 'overall cost', is that for the set up and actually driving the piles, plus materials etc.?

 

Also - I saw you mention a trusted SE, any chance you could PM who that is? Thanks.

[ToughButterCup]

Its no secret, loads of us have used them : Tanners in Eire. Superb. Saved the price of their fees many times over.

[The Reverend]

4 hours ago, ToughButterCup said:

The set up cost for our piles was about £5000. The additional cost of (unplanned - 'where we might want to put a garage'  ) piles  was £50 each. We threw in a couple of others between our piggery and the house for when the piggery is extended 'into' the house 

 

Have a read of my stuff about piling. Overall cost for 146 sq m was £6500.

@ToughButterCup That sounds very reasonable for piles. Who did you use, if you don't mind me asking.

 

[ToughButterCup]

 

[Post and beam]

20 hours ago, AppleDown said:

oak tree in a conservation area. It's a big boy - no TPO

This might be of relevance.

Our recent planning permission is in a conservation area in north Hertfordshire and we have a number of trees. Particularly 3 large walnut trees. No TPO or so i thought. But, it turns out that the very fact its a conservation area means blanket TPO by default. They dont nail the little metal tags onto trees to identify the protected ones like they used to years ago.