Does tanking out really help?

[NomsQualityStreets]

Currently live in an old cottage style terraced property. We're a little short on space so we have decided to have the currently very damp cellar tanked out and dried and put some shelves in to make it into a pantry type/ storage room.

The cellar has flooded in the past, about an inch of water got in. We don't live at the bottom of a hill but there's a grate (I think that's what it's called?) underground in the cellar wall that leads onto the garden and that's how the water got in in the past during bad storms. It hasn't happened for about 2 years now.

I'm not 100% on what to expect so my question is will tanking it out prevent the damp from coming back altogether? Or is it something that will have to be redone?
Will they do something to prevent a potential flooding or is that just something we have to live with? (I don't know the purpose of the grate)

I just wouldn't want to spend thousands on a tanking out job just to have the mould and damp eventually come back and having to redo it again.

Does anyone have any experience/knowledge of this?

You need a sump pump as well to carry water out. A cellar conversion company will be able to advise you.

Thanks @wowfudge I will have to ask them.

It's only flooded once or twice and not for the past 2 years but there's still a risk I suppose.

Would it mean nothing could be kept on the floor just in case?

You can have the floor tanked as well, but it won't stop water getting in. Tanking provides a barrier making the inner walls dry and water runs down between the original wall and the tanking membrane and has to be pumped away. Floors can also be tanked. Tanking restricts what you can fix to the walls and how it is done because drilling through the membrane would create a hole for water to penetrate through.

To clarify - tanking stops the tanked room from getting wet. There will still be moisture getting in behind the tanking membrane which then has to be pumped away, preferably down a drain.

We had a cellar that flooded a couple of inches some winters when I was growing up and it was fine for storage - we just put storage furniture on top of brick plinths. It wasn't mouldy because there was plenty of ventilation. If you're only planning to use it for storage, tanking it sounds like an awful lot of expense and disruption.

Tanking isn't as good as a membrane plus pump as eventually water will find a way through tanking whereas with a membrane the water is still there behubd the membrane but is drained away.

www.prlog.org/12086953-effective-basement-tanking-and-cellar-conversions.html

www.restorationuk.com/about-restorationuk/restorationuk-news/how-to-tank-damp-walls-tanking-and-waterproofing-to-treat-penetrating-damp

Thanks for the links @Rightmovestalker I'll have a look at them tonight.

@JustAnotherManicUsername there's no ventilation it's a small underground cellar in an old stone terraced house, the damp is really bad you get a waft as soon as you open the door. We've put some leftover bits of wood from when we did the kitchen in there and DP took them out last week and they went green in parts and started to slowly rot.
We don't go down there at all ATM.

Thanks @wowfudge all we need is a row of shelves on one side of the cellar I think we can probably get some small freestanding ones from IKEA so to not drill into the wall?
We want to use it for storage of non perishables and other bits like dog food, nappies etc as we live rurally and often buy in bulk to save having to make lots of trips to the shops everytime we run out of one thing. I was also hoping to put a condenser tumble dryer near the entrance but judging by the flooding risk I'm guessing it should probably go on a little platform or something to keep it raised in case it does ever flood?

"there's no ventilation "

then start with that. It's the essential first step. Usually air bricks on at least two sides of the building will make a big difference. On all sides is better, so whichever way the wind is blowing there will be a through current. Water vapour is lighter than air so will rise towards the ceiling. If the ceiling of the cellar is below ground level, use "periscope vents" or maybe dig away the ground from the walls if it has been raised since the house was built.

Cold is good. Warm and damp promotes rot.

You can insulate the ceiling if you want, it will prevent draughts into the house. Loft mineral wool is fine.

As previously suggested, a membrane and pump system would be best. It’s not cheap though.

How big is your cellar - it seems an expensive process to go through just to create a store room. Could you create a habitable space (play room, tv room) and have a cupboard in there for storing your items?

@AppleCrumbleCake it's a very small cellar and arched/rounded off ceiling, I can only walk standing up straight if I'm walking straight down the middle of it.

It's probably a bit expensive but it will mean we get rid of the clutter and lots of bits currently taking up room in the kitchen and lounge which rarely get used. The house is tiny and there's 4 of us + DDog so any storage makes a massive difference.