Tanking a cellar - is it worth it?

Carrotline

Having a second viewing of a property tomorrow, which has a cellar. Current occupier is using it to store tools, and it hasn't been damp-proofed.

We've been thinking about the development potential of this place, and a couple of people have suggested turning the cellar into a study or "play room" for my other half

However, I know tanking the basement isn't going to come cheap, but does anyone know what kind of return on investment we're likely to get if we do?

Will it just protect against damp and/or will it offer any protection from flooding?

We're planning to live there for at least five years.

NewtoDIY

To do properly, this is one of the most expensive jobs you can do! You should think very carefully about the actual cost of doing this. People often ruin a tanking job by piercing it - one nail through and you'll have to start over.

Carrotline

NewtoDIY wrote: »

To do properly, this is one of the most expensive jobs you can do! You should think very carefully about the actual cost of doing this. People often ruin a tanking job by piercing it - one nail through and you'll have to start over.

How expensive are we talking?

NewtoDIY

Have a look at the buildingsheriff website. It would be worth calling around for some quotes, even if to get a ball park figure.

BlueC

Tanking is a big topic, if you do proceed with the purchase you need to do some research of your own and speak to as many people as possible.

There are different methods and as pointed out the costs can be very high. However they needn't always be... it's one of those jobs where specialist firms feel they have the right to charge the earth because it seems such an extraordinary thing to do (and this myth is being perpetuated here) whereas in reality it is a reasonably simple construction process and the materials are not extortionately expensive in themselves. It isn't even particularly labour intensive, especially if no excavation needs to take place.

As for whether it would add value or a return on investment, it depends on the property itself, what you ultimately do with the newly tanked cellar/basement, and whether you get full building regs sign off for the tanking and conversion work. Without sign off it isn't even considered as a room when coming to sell (same as loft conversions that are not done to standards) so adds zero value. With sign off then it could add value, but naturally adding 2 new ensuite bedrooms down there would add more value than making a small playroom.

You didn't say how big the basement (or property) is, whether it is fully excavated, current value of property compared to market, whether others in the street have done same and whether they sold for me, etc, so any further insight is pretty much impossible.

I guess the short answer is: a property with a basement that has potential to be converted at some point in the future is better than the same property without the basement. At least it gives you options.

BlueC

Oh, and just to answer about the damp/flooding thing... if by flooding you mean water ingress through the floor/walls of the cellar then yes a tanking system will provide this protection. Modern cavity drain systems with a pump and sump can withhold a lot of water - you see bone dry cellars that were previously submerged under water.

If you mean water coming in from above (e.g. if the property is situate in a flood plain) then no it won't prevent that - in fact it would be awful because the water would have nowhere to go. Would make an interesting underground swimming pool though!