Damp Garage Walls

[NetworkSnow]

Hi all,

First post so if in the wrong section please let me know!

We have noticed damp penetrating into our garage rear wall (built around 2003). We initially thought this was the roof due to a larger leak, but after having that separately repaired, this damp patch has remained and persisted for a few weeks. The rest of the garage has dried up.

I have made inquiries with local builders for their recommendations, and so far have obtained two quotes and I am waiting on a third.

One recommendation was to dig out behind the garage (see in the picture) and fill with stones to allow for easier drainage. A second recommendation was to dig out to a meter down and leave the space empty, with concrete blocks used to hold the ground up next to the shed.

These quotes range from £500-£1.5k, and some advice on the best solution would be appreciated!

We've had other costly repairs with the house so just trying to not let this get out of hand! I can post the quote breakdowns if needed.

Many thanks for the help.

 

[JohnD]

which wall of the garage is wet?

where does the garage gutter drain to?

where does the shed gutter drain to?

do the gutters leak or overflow?

where is the garage DPC?

stand back and take some wider pics

 

[NetworkSnow]

Answers:

which wall of the garage is wet?
- The side next to the shed, on the right of the image.

where does the garage gutter drain to?
- It pipes into the ground, there's a drainage system. The black gutter goes into a brown larger pipe under the tiles. I don't think this is the issue.

where does the shed gutter drain to?
- Unfortunately the shed has no gutter, so the floor in between the gap.

do the gutters leak or overflow?
- The garage gutter, no. This was checked when the roof was repaired, and this drains normally.

where is the garage DPC?
- I'm not certain. Is there a way to verify this? This is where my DIY knowledge is limited.

stand back and take some wider pics
- Will do now!

 

[NetworkSnow]

Have taken some wider photos, and a close-up if where some of the damp-proof membrane is visible.

The garage inside at this location is dry. Only areas above this point are wet.

 

[Deleted member 292770]

dig it out . install a doubled up layer of quality dpm up against the wall higher than the stones and lower than the dpc and fill back in.

 

[NetworkSnow]

dig it out . install a doubled up layer of quality dpm up against the wall higher than the stones and lower than the dpc and fill back in.

Can anybody else recommend this course of action? Cheers!

 

[Deleted member 292770]

How many opinions do you need ? And what’s the deciding factor of who is right or wrong?
You’ve had two builders and several suggestions .

 

[NetworkSnow]

How many opinions do you need ? And what’s the deciding factor of who is right or wrong?
You’ve had two builders and several suggestions .

I was simply looking for a general consensus. The two builders vary massively in opinion and price. I’m just looking to make the right decision without spending a small fortune.

This feels like a fair ask?

 

[Deleted member 292770]

You’ll need a mattock or wide pick to drag the stones out and a roll of Damp proof membrane and plenty of elbow grease. call it 100 quid.
You’ll need to go 5” below the dpc which is more than likely at garage floor level.
Double or treble the dpc so that it sits 5” lower than the dpc and temporarily batten the top of it to the wall until you’ve finished backfilling.
The only questionable aspect would be any rain water getting behind the membrane , which is negligible and should not cause an issue unless that wall is subject to frequent driving rain.
If it is , a lead or cheap lead substitute could be cut and sealed into the mortar bed just above the membrane to deflect rainwater over and away from it.

 

[Notch7]

I reckon half the problem is the shed roof discharging onto that area.

my first job would be to get some gutter on the shed.

does the garage down pipe actually go somewhere - it’s not unknown for downpipes to stop to Earth, no underground connection.

once you’ve done that, if the damp is still there, dig out some of that stuff.

I don’t know enough to be sure DPM against the wall would stop damp as it would be open at the bottom

 

[Deleted member 292770]

I don’t know enough to be sure DPM against the wall would stop damp as it would be open at the bottom

Providing its lower than the dpc it can’t fail. water doesn’t run uphill.

 

[NetworkSnow]

I reckon half the problem is the shed roof discharging onto that area.

my first job would be to get some gutter on the shed.

does the garage down pipe actually go somewhere - it’s not unknown for downpipes to stop to Earth, no underground connection.

once you’ve done that, if the damp is still there, dig out some of that stuff.

I don’t know enough to be sure DPM against the wall would stop damp as it would be open at the bottom

Adding a gutter on the shed seems simple enough, will look into that!

Question is how I identify where the DPC begins to ensure any membrane goes far below it?

 

[Deleted member 292770]

Adding a gutter on the shed seems simple enough, will look into that!

Question is how I identify where the DPC begins to ensure any membrane goes far below it?

set the membrane 5” below internal floor level.