Damp and Timber Specialists for 50 years

Alun Newman from BBC Radio Solent talks to Alex Marsango, Expert Surveyor from Prokil, Damp and Timber Specialists in Bournemouth about all things basement extensions and conversions.

Recorded on the Sasha Twining show, BBC Radio Solent, Friday 18th May 2018.


When the cost of the house is so high there’s a brand new trend, Don’t Move, Dig Down. Alan Newman’s on the case.

Sasha I’m walking down Holdenhurst road just on the edge of Bournemouth. Why am I here today? Well when they look at house prices and the cost to move average UK house price around £226K, cost to move nearly £9K.

So if you’ve got a house just under half the million, cost to move is nearly £20K that could be why we’re seeing an increase of over a 180% in applications for basement extensions. Yes. Have you ever thought about digging out the basement and putting in the kitchen and the extra room for the children. Why move why leave your neighbours and a lovely place to live? It’s so expensive. Could now be the time to get the builders in to dig the basement? How much does it cost? How easy is it and can anyone do it? I’m off to Prokil Damp & Timber Specialists in Bournemouth to find out.

Offices up and down the country. Alex Marsango is with me, he’s one of the surveyors here and we are talking basement’s. The bottom line and I’ve got a whole bunch of really straightforward questions for you Alex. The first one is this:

Can anybody if you own your own property and you’re a sensible go for basement conversion?

In essence, yes they can.

There’s no particular strict rules or laws as long as it’s sensible you’re not a conservation area? Those kind of obvious things you can go for it?

Yes you can.

Okay let’s take an illustration of the detached property rights because my simple illustration when you dig down does the client come to you and say this is what I want and you work out the budget, can you go two floors down, what are the rules?

Yes you can, ultimately it’s down to the person who wanted to expand their property. And what we’re finding is that people are normally starting off with a single story extension or those people who have slightly larger budgets are potentially looking at getting down multi level. But we generally advise to start off with a single and then look to progress from there.

How do you start digging a hole without knocking the house down?

It would a first thing that we would recommend is that what we can do for you is actually put you in touch with your local planning officers just to see if you do need any planning. If you do not need planning then it’s always worth speaking to the Building Regulations departments. And then after that what we can do for you is we would put you in touch with some structural engineers who would come round to do a site assessment to assess the feasibility of actually digging down. So once you have that all approved then we would actually look to excavate under your property. So we actually go out from the outside not from inside as a lot of people may often think and what’s involved is excavating from the outside, opening up putting in supports and then introducing something which is a bit like a conveyor belt to actually take away the waste earth or whatever rubble you have from underneath the property.

What’s stage then do you stop throwing in some sort of concrete to make it watertight?

Well that’s a that’s a good question actually the honest answer is it depends more sort of structure you have and what type of supports you have within your basement. There are different options available to you. I won’t bore you with the different British Standards codes which cover this but there are different options depending on what finish you would actually like. So as you quite rightly mentioned going in like a mine, once you get down to the depth you have a fully excavated then that’s when you look at what options you have, so you can either have a membrane system or you can have a structure which is designed to be inherently water resistant but otherwise build something and then added to it afterwards to make it waterproof.

We just want it to look cool, and glass and glitzy with the new kitchen in but of course you guys want to make sure it’s watertight and it does everything it’s meant to do?

Answer me this about the amount of waste because when you dig a hole there’s always more than you think, does it generate an enormous amount of waste that most clients go I can’t believe how many skips they need?

Yeah absolutely. This is something a lot of our clients find quite surprising actually is the amounts of waste which is generated and it’s not just a case of having one or two skips as a case of having multiple skips coming continuously throughout the excavation process.

We got a four bedroom detached house as our style, we’re going down one level in order to put in a cinema room maybe a kitchen, I don’t know, how long how much hassle?

Well the length of time it can take it’s also depends on planning whether or not you need to get that approved but let’s say once you have approved then you’re probably talking about a process of around three to four months from start of dig to actually being able to relax in your cinema room or work out in your gym or do your work in your office space.

And the question that everyone screaming at the radio now is how much is it going to cost me? Because the idea is that I’m not moving I’m saving all those fees but now I’m going to have a basement. What sort of money am I talking?

The honest answer is for a basement if you have something which is already in situ then you’re probably talking in around £15 – £20k just to install the waterproofing system, ready for you to decorate. If you wanted something fully excavated all singing all dancing then you can be talking anywhere between £30k up to £300k.

They are on the increase, just finally you get to see some that you think you know recently you’ve seen and done and thought that is wonderful?

Yeah absolutely there’s a one quite recently which show we it ended up in Reading and the client wanted to excavate, which we did and build the supports in a fully refurbished the basement was complete. They had nice glass opening doors out into a light well and the client installed a lovely cinema with 12 seats with a lovely surround sound system and it was definitely the envy of the street.

More than £30k! Last last question I promise. The presenter of the show Sasha Twining said to me that she heard a rumour once that with good basement conversions sometimes they leave the digger and they bury it?

Have you ever heard of anyone leaving the digger?

No, I’ve never heard of anyone leaving the digger but there are other things that we have found whilst excavating .

I bet you have, thank you so much Alex Marsango, from Prokil Damp and Timber Specialists, If you want to dig down they can do it for you.


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