Concrete shed floor with no dpm - what can I do?

mrlee

Hi folks.

I have a shed a little bigger than a single garage that I plan to restore a car in. It has wooden walls & a corrugated tin roof but it’s currently the concrete floor that’s causing me an issue. When it rained heavily a few weeks ago I noticed a puddle of water on the floor but I don’t think it came from the roof (although it is possible), I think it came up through the concrete. My uneducated guess is that there was no dpm put under the concrete when it was put down many years ago. Might be entirely wrong though, not sure if it’s possible?

Essentially is there anything cheap I can do? I don’t mind if the floor level has to come up a bit - if I put any other surface over the top (like brick pavers?) would the water just be sandwiched between the concrete & the new dpm? Not the end of the world but I’d rather not be laying in water if possible.

It’s not my house but I’m happy to spend a little to make it nicer, obviously don’t want to go crazy spending though

EachPenny

mrlee wrote: »

I have a shed a little bigger than a single garage that I plan to restore a car in. It has wooden walls & a corrugated tin roof but it’s currently the concrete floor that’s causing me an issue. When it rained heavily a few weeks ago I noticed a puddle of water on the floor but I don’t think it came from the roof (although it is possible), I think it came up through the concrete. My uneducated guess is that there was no dpm put under the concrete when it was put down many years ago. Might be entirely wrong though, not sure if it’s possible?

Essentially is there anything cheap I can do? I don’t mind if the floor level has to come up a bit - if I put any other surface over the top (like brick pavers?) would the water just be sandwiched between the concrete & the new dpm? Not the end of the world but I’d rather not be laying in water if possible.

It’s not my house but I’m happy to spend a little to make it nicer, obviously don’t want to go crazy spending though

I wouldn't have thought the lack of a DPM would cause a puddle on the floor. My money would be on a leaky roof, or possibly condensation dripping off the underside of the roof.

Before spending any money do a simple 'bucket' test - put a bucket or washing up bowl where the puddle was and see if you get any water in it. If you do, then you know it is coming from above and not below.

If you are in a hurry for answers then you can always use a hosepipe to simulate rain. And you'll get an idea about condensation if you check the underside of the roof (usually best during the first few hours after sun down on a day with fairly clear skies). Alternatively, tape a piece of kitchen roll on the underside of the roof and see if it is wet in the morning.

ETA: Also check the possibility of the door(s) or window(s) having a leak.

mrlee

I just got out of the shower & whilst in there I thought “I must amend my post to add the condensation fact” but you beat me to it. The reason I thought it was coming up was because of the puddle being in a slightly covered area - in hindsight I guess it could be running off something else to end up pooling in that point.

The tin roof is a bit of a concern because of the condensation so maybe I’ll look at switching it out for some plastic roofing in the future if it is causing the puddle problem.

Good call with the bucket idea :beer:

EachPenny

mrlee wrote: »

I just got out of the shower & whilst in there I thought “I must amend my post to add the condensation fact” but you beat me to it. The reason I thought it was coming up was because of the puddle being in a slightly covered area - in hindsight I guess it could be running off something else to end up pooling in that point.

The tin roof is a bit of a concern because of the condensation so maybe I’ll look at switching it out for some plastic roofing in the future if it is causing the puddle problem.

Is the floor bare concrete, or does it have any kind of coating?

With bare concrete I would normally expect it to be sufficiently porous to absorb a lot of the water before it can flow very far across the surface.

On that subject, if it is bare concrete you might want to invest in some floor paint, especially if the restoration involves any painting. It is surprising how easily concrete floors can wear, and that wear generates dust which can be a killer for restoration work. My family are restorers of various old machines (hence my knowledge of the condensation issue ) and all work is now done in sheds with painted floors. However, be aware of the slip risk with water and oils on painted floors and go for an anti-slip version if your budget allows.

mrlee

EachPenny wrote: »

Is the floor bare concrete, or does it have any kind of coating?

With bare concrete I would normally expect it to be sufficiently porous to absorb a lot of the water before it can flow very far across the surface.

On that subject, if it is bare concrete you might want to invest in some floor paint

It’s bare concrete, far from a glass finish so it has it’s own anti slip in place! Had a quick look & paint doesn’t seem too badly priced so I might put some down before I bring the car in. I don’t anticipate painting in there but curing the condensation (if that’s the problem) will be key as I don’t want the parts I repair to go rusty. Maybe one or two of the rotary fans that are driven by wind passing across them might help to keep the air moving through?

bloss0m

My money is condensation too, you could insulate the roof with a false ceiling using insulation boards.

mrlee

I’ve put a bucket in there for now, just need to see if the water is coming from above & then whether it is condensation or a leak. Working on tidying it out at the moment & once it’s clear I should be able to figure out what’s going on a little easier.

Thanks for your help folks!

Mistral001

The lack of DPM in the concrete floor could give rise the floor being damp, but would not cause a puddle. The water is either coming from a leaking roof or condensation forming on the underside of the roof/ceiling and then dripping on the floor.