Trial pit to test foundations

darrend2812

Hi all,

We're in the process of expending on top of our existing garage. The architect/structural engineer mentioned we need trial holes to check the foundations however has suggested these could be done inside the garage rather than outside. I've searched on various sites and can't understand why they are advising this inside. Any thoughts? 

DRP

We are replacing an existing conservatory with an extension and reusing the foundations.

We dug an external trial hole on each elevation to show depth and width of the foundations. Council BC were happy with this.

Woolsery

 Perhaps if you are stripping out soil from the inside anyway they think it will be less disruptive or cleaner. If the roof is still on, it will also prevent heavy rain filling up the holes, though it won't affect holes filling with ground water.

FreeBear

darrend2812 said: We're in the process of expending on top of our existing garage. The architect/structural engineer mentioned we need trial holes to check the foundations however has suggested these could be done inside the garage rather than outside. I've searched on various sites and can't understand why they are advising this inside. Any thoughts? 

Generally, there is a thick slab of concrete inside the garage. Without a lot of effort, it is difficult to get through this slab. Outside, there is often a much easier surface to break up (slabs, block paving, gravel) reducing the effort required. If you want to dig your test pits inside, there is nothing to stop you, aside from cost.

stuart45

The SE would be the best person to ask. 
Have you got a single skin garage and are putting a cavity wall over the top using steels to take the upper internal skin?
As it will need holes for piers dug out, it may be that he thinks the trial holes could be dug out where the piers go.

EssexExile

They did our test holes inside, then did all the underpinning from the inside. I've no idea why but they seemed to know what they were doing.