Damp-proofing a garage
Follow Peter Clayton as he performs a DIY repair to his damp and cold external garage.
Back in the August 2021 issue of CM I wrote about an overdue subframe restoration on my wife ’s 2006 R50 Mini One. An obstacle to add to my growing list at that time was resolving the issue of my rather dank and drear y garage. The internal humidity would reach levels that slowly turned fixings, bare panels and my precious tools into corroding pieces of modern artwork. The following summer I set about finding a cheap but reliable fix.
After some research, it appeared that I was far from alone in this predicament; thousands of single-skinned residential garages across the countr y succumb to this malady. The problem often manifests from rainwater seeping into the walls; the situation often made worse when a part of the wall structure is underground, where the soil acts as a bridge to allow groundwater to seep directly through the wall itself (through hydrostatic pressure).
What compounds the issue fur ther is in the garage construction itself. Such buildings aren’t classed as dwellings which will not fall under as stringent construction standards, so corners can technically be cut. On my garage for example, the builders got away with using a full row of fewer tiles on each side of the pitched roof – meaning the overlap of each tile was smaller, allowing capillar y action of rainwater to seep into the oriented strand board (OSB) underneath, soaking it through. Additionally, the water proof membrane on the concrete f loor was laid with little attention and in places breaking the surface at the edges!
The solution
I employed my local roofer to throw another row of tiles on the roof and shuff ling the rest up, which thankfully resolved the incontinent ceiling. The walls, however, remained problematic for a while longer. I initially tried spraying masonr y waterproofing sealant on the outside brickwork. This was a case of brushing down the brick of any moss or dirt, then liberally spraying a few clear coats. This had some success as any rainfall rolled off the brick and mortar rather than being absorbed by
