Foundations within RPA

[Island Lescure]

I may be getting a job that requires the installation of foundations within an RPA. This will obviously require a method statement.

 

I will probably go for the pile and beam design as on the attachment.

 

Questions:

1: Any idea whose document this is? I found it online and would like to include it into the method statement. There is no copyright that I can find. I do not want to impinge upon copyright issues. Is this a generic method statement with free use or does someone know of another?

2: Hand digging with pole augers is specified in this attachment, to discover roots and subsequently decide pile placements. I have seen that air spades are also used but this would obviously be more costly and not necessarily more effective, in my view. Would there be any reason to use an air spade?

 

Any other comments or suggestions welcome.

 

Thanks,

 

Island

foundation within RPA.pdf

[Chris at eden]

Looks like a slight variation on the Abby Pynford system. Be careful how involved you get with specifying engineering works as it is outside of your remit or expertise. Your advice should be coming from a tree protection point of view so if you spec the works make a point of saying it needs to be signed off by a competent person. Ideally you would work with the engineer to spec the works.

 

Remember if you spec that system you will need a specialist for to install and its expensive. Most builders kick off when you start talking about hand digging in my experience.

 

Ruskins will do your arispade work for just under £1k a day inc. VAT (2015 prices - last time I used them) so yes expensive but the LPA may insist. Depends on the TO.

 

Cheers

[Island Lescure]

Thanks Chris. Just googled Abby Pynford system and it turns out the method statement is indeed theirs.

I will ask what the architect or engineer has in mind first as I think they already had this as an option. It is for a 2.7 meter single storey extension so there should not be too many piles and as such not much digging.

[kevinjohnsonmbe]

Seems like a faf for a 2.7m single storey extension? Expense and hassle of constructing within RPA and probably under canopy (if not now but in the future?)

 

Is it worth the hassle?

[Island Lescure]

I have not been to site yet so I am just looking at my options. It is in a conservation area in a prominent location so it can only been done conforming to the area's style under so and so conditions.

[Chris at eden]

Seems like a faf for a 2.7m single storey extension? Expense and hassle of constructing within RPA and probably under canopy (if not now but in the future?)

 

Is it worth the hassle?

 

 

I was involved in one a while ago where we cantilevered the last metre or so of the house to avoid the RPA. Bonkers really but that's what they wanted.

 

I have one now which is similar to this one. Single storey rear extension, 2m projection. There is a knackered old oak with no visibility but still has a TPO recently made. I said fell the tree, TO said no, I said go to appeal but they don't want to so they are reducing the projection to 1m. What's the point!

[Dave177]

We have excavated quite a few piling holes with airspade on similar projects. Generally we go to 1m by hand then it is augered from there. You have to have flexible architects on this because you cant tell where the gaps in the root system are going be before you start investigations, so you may end up with 2 piling holes 1.2m apart but a 3rd would have to be at 1.6m etc.

 

The benefits of an airspade over hand digging are obviously minimal damage to the root system, and speed as it is usually quicker to excavate a piling hole like this with an airspade than carefully hand dig.

 

See Arboraeration | Tree Healthcare Experts for further info

[Island Lescure]

I was involved in one a while ago where we cantilevered the last metre or so of the house to avoid the RPA. Bonkers really but that's what they wanted.

 

There is supposed to be a Monterrey cypress here.

 

Would you have and not mind showing details of the cantilevered construction? That could be an idea if the foundations only just go into the RPA.

 

Cheers!

[Island Lescure]

We have excavated quite a few piling holes with airspade on similar projects. Generally we go to 1m by hand then it is augered from there. You have to have flexible architects on this because you cant tell where the gaps in the root system are going be before you start investigations, so you may end up with 2 piling holes 1.2m apart but a 3rd would have to be at 1.6m etc.

 

The benefits of an airspade over hand digging are obviously minimal damage to the root system, and speed as it is usually quicker to excavate a piling hole like this with an airspade than carefully hand dig.

 

See Arboraeration | Tree Healthcare Experts for further info

 

Cheers!

[Chris at eden]

There is supposed to be a Monterrey cypress here.

 

Would you have and not mind showing details of the cantilevered construction? That could be an idea if the foundations only just go into the RPA.

 

Cheers!

 

It was for a previous job so don't have the details but just Google image it, you will see what I mean. The benefits over piles were mainly cosmetic, it looked cool.