workshop flooring and damp

[johnnyb]

my workshop has a concrete floor without a dpm. it was built in the fifties and the concrete floor was added after the build(not a slab) their are areas of damp and the floor has many cracks. i think painting may be out of the question, so i may use rubber matting not stuck down at least 5 mm thick wall to wall. one wall also has soil behind it and is very damp. i have disk cut the floor to separate it from the very damp wall(not completely as the disc only cuts 2 inch. my question is how do i address the very damp wall with the soil behind(another building has been built very close so the soil bank cant be accessed.) will the rubber matting help with the damp/ humidity. or just make matters worse.

 

[Mike.C]

I don't know much about damp proofing, but I did see a program where they had a similar problem, and to cure it they took a number of bricks out of the wall every few feet and held them up with needles (?).

They then dug the soil out, laid some damp proof membrane (plastic type sheeting I think) and then replaced everything.

This is a very basic run down of what they did and I have probably missed a lot out, but it may give you some idea of what can be done.

Cheers

Mike

 

[RogerS]

Not an expert but have you thought of applying Synthaprufe to the walls and flooring?

 

[Paul Chapman]

my question is how do i address the very damp wall with the soil behind(another building has been built very close so the soil bank cant be accessed.)

I reckon that, as a first step, unless you can find a way to remove the soil that is against the wall, you will not cure the dampness

Cheers

Paul

 

[Stoday]

Asphalt membrane, laid hot.

Not a DIY job though because you need a heater for the asphalt.

 

[Jorden]

Hi John

I was thinking exactly the same thing as Stoday, the only real solution would be to tank the room, asphalt the floor and walls up to above the damp line. If you are going to go that far, I wonder if it might be a good time to replace the concrete floor with a wooden one, or maybe another concrete one with heating pipes in it - just a few thoughts :shock:

Dennis

 

[llangatwgnedd]

Tank the room with Bitumen Paint.
Quote from a website

To: BS3416:1975 Type 1 and 11 Black bitumen paint is used for all metal protection against corrosion. Also as a water proof coating for concrete, stone etc. Taint free coating for drinking water tanks.

 

[johnnyb]

iinteresting replies as ashphalt would cure the problem 100 percent. is this an expensive process? a firm near us advertises this service. i have tanked the damp wall with liquid damp seal. it seems effective especially now i have cut the floor away from that wall. the only other solution i can find mentioned is moisture curing polyurethane( from the collins diy guide) but i can only find(what i think) is the product a decorarting direct. under floor paint but it is very expensive also. rubber matting would work but is really expensive. is ashphalt basically tar. and will it fill cracks.? this seems like the ideal solution as it will fill the small gap in the floor i have cut as well.

 

[Stoday]

Asphalt is, I think, basically tar loaded with sand. It sets hard and smooth when it cools and will fill cracks. I have used it in an extension I built some years ago and in a wine cellar earlier this year.

For cost, look for a local asphalter and give them a ring.

 

[Shultzy]

After you have put the liquid damp seal on the damp wall I would put in a suspended wooden floor (much more comfy on the feet).
Chisel a horizontal groove along the damp wall above the damp.
Tuck end of heavy duty 1200g DPM into the groove and seal with mastic.
Lay rest of DPM down wall, across floor and up other side.
Lay 4x2 timbers across the short span of the floor on bricks laid square to the timbers at 12" centres.
If the concrete floor is not level set the bricks on a mortar bed.
If you are putting in skirting boards, glue them to the floor - DON'T puncture the DPM

 

[johnnyb]

the suspended floor is a great idea but i have recently put a mezzanine storage piping floor and the headroom is now quite limited. i have managed to find a source of moisture curing pu sealant.........pond sealant called g4 available from any aquatic supplier.cracks can be filled with the resin mixed with dry sharp sand. you just paint it on putting 3 coats on in quick succesion and hey presto its about £50 for 5 litres it is quite a difficult material to source . after regular floor paint will make it look nice. also rather than skim with plaster the bitumen can be painted with emulsion paint, gypsum is best avoided in outbuildings. the wonders of modern technology.

 

[ivan]

You can get Johnstones Epoxy Resin floor paint at Leyland* decorators centres, who seem to sell to anyone at trade prices. This will bond like XXX and protect your polyurethane waterproofing from foot damage.

* Leyland, the cheapie brand (Kalon Coatings?) bought out Johnstones, a premium paint mfr.