damp proofing garage?

[damson]

We've just bought a new house and the floor of our detatched garage seems to be lower than the surrounding slab paths which may be contributing to the nasty damp patch in the far corner. The previous owner built a wooden shelf from sleepers, which rests on sleepers (so like an upside down U shape) and the far corner of the garage is particularly damp where the sleepers rest against the wall and the surrounding path is higher.

I want to convert the garage into workshop and storage area. There's a small ventilation brick in one corner and a boarded up window which I'm going to replace with a door (new lintel etc)

I'm definitely getting rid of the shelf built from sleepers but what else should I do to make the garage less damp? It's only the far corner walls which appear to be the problem. Is there anything I should / could coat the walls with? Should I raise the floor height of the garage / install a damp proof course?

all thoughts and advice appreciated

thanks in advance

Damson

 

[damson]

Any takers? Any thoughts? Any questions?

thanks again in advance

Damson

 

[dhutch]

Watching this as im also looking to improve and dry out my newly aquire garage.

Is there anywhere lower for the water to drain? Wall construction? Damproofing? Age?


Daniel

 

[damson]

Here's hoping we get some input from the experts!

 

[RedHerring2]

Here's hoping we get some input from the experts!

How about answering dhutch's questions. Thatl may be a start.

 

[damson]

Sure - wasn't sure who dhutch's questions were aimed at.

The garage is constructed of single skin concrete blocks and then rendered with pebble dash on the outside. It has a concrete floor and a flat 'felt style' roof which is in good condition supported by wood joists. It must have been built after 1950 which is when the house was built but I don't know when. The door is a modern up and over design. There's no damp proofing layer and the previous owner built up the path which surrounds the garage on two sides (by laying another layer of paving stones) over the existing ones. There is however a carport roof over the back of the garage and a flower bed along the side with the path so in theory any rain water should go into the soil not seep into the walls.

thanks again!

 

[RedHerring2]

Thge single skin blockwork will be permanently damp from ground level upwards, decreasing in dampness the further up it is.
Short of inserting a dpc you could try tanking the inside of the walls.
You also need to address the lack of dpm on/in the floor. This can be painted on with something like Synthapruf, but wouldn't last long without some protection from a screed or similar, but you don't want a screed in a garage. (Although I note you want to use it as a workshop). So a further slab of concrete on top is another option with a dpm.
That further slab of concrete, I would have thought, needs to be at least 50mm thick otherwise it'll break up over time.

 

[damson]

Thank you!

So if I inserted a dpm in the walls I would also need to dpm the floor?

If I tank the walls I wouldn't be able to drill fixtures into the walls, would I?

Are there good DIY options for inserting dpm or tanking the walls? Is a dpm the best option?

Could I add a wood floor to the garage floor once it was dpmd rather than concrete? I have no intention of parking a car inside it!

thanks again for further thoughts

Damson

 

[RedHerring2]

So if I inserted a dpm in the walls I would also need to dpm the floor?

Yes. dpc in the walls, dpm on the floor.

If I tank the walls I wouldn't be able to drill fixtures into the walls, would I?

The tanking could just cover the lowest 1 m or so.

Are there good DIY options for inserting dpm or tanking the walls? Is a dpm the best option?

You might be able to hire the machine for chemical injection, but you'd have to know what you're doing. I have no experience of creams, etc.
You'd have to ensure that the external ground level is below the dpc in the wall.

Could I add a wood floor to the garage floor once it was dpmd rather than concrete? I have no intention of parking a car inside it!

Ues, you could have a floating wooden floor over the dpm.

 

[cotswoldbuilders]

It would help a lot if you reduced the outside ground level, it should be minimum 150mm below f/f/l

 

[damson]

Just wanted to say thank you to everyone for their advice - I've got a good idea now of what I need to do now.

Can I just check what f/f/l stands for?

And does anyone have any product recommendations for the wall tanking?

thanks again

Damson

 

[cotswoldbuilders]

F/F/L Finished Floor Level

 

[RedHerring2]

And does anyone have any product recommendations for the wall tanking?

thanks again

Damson

Sand/cement render with a waterproofer is the norm, I believe, possibly with SBR added or used on the wall prior to first coat.
You could try a paint-on product like Synthapruf. It's not particularly cheap though. Aprrox £20 per 5 litres.
Make sure it overlaps with the dpm in the floor.

The Synthapruf on the wall may need some protection.

 

[damson]

thank you so much everyone for all your advice and thoughts!

I will let you know how I get on!

Damson

 

[damson]

thank you so much everyone for all your advice and thoughts!

I will let you know how I get on!

Damson