Lucky for 20 years and then one day...
A newbuild cellar constructed in a relatively modern house in Powys, Mid Wales, had not suffered from anything other than moderate damp; the sort that is only really noticeable with a meter, until disaster struck! Of course when under ground it is always best to plan for the worst and unfortunately the builder hadn't built the basement to be waterproof.
One night water streamed in through the walls at the floor/wall joint and pretty much ruined the floor and furnishings of the room.
Conifer Basements were called in to help with the cellar restoration. We first recommended that the floor screed should be removed as it was laid on top of non-waterproof insulation and was a perfect place to trap water. If water pressure builds up it can even break a concrete slab so it would have had no trouble in breaking a weak screed and destroying any reparation work. Also the back of the room had an open drainage channel with water in it, topped with chipboard - Not ideal!
Once the floor was taken back to the concrete slab we were able to get to work installing the sump chamber and pump along with proper drainage channels ready for the cavity drain system to be installed. The first four pictures opposite show a very quick walk-though of the installation. After the membranes had all been installed and taped-sealed, etc. the building work began.
On this project the customer opted for a floating timber floor laid on 75mm of insulation boards. We usually install 25mm insulation between the battens in the floor too; this increased the thermal efficiency but also provides a more solid floor as it removes the voids. Once the battens are laid one way, the chipboard t/g flooring units can be screwed down the other; making the entire floor one unit. This makes it feel firmer under foot and makes sure that the boards cannot part.
Once the floor was complete, new stud-walls were constructed around the perimeter walls with 75mm Drytherm battens insulating between the timbers. Once complete the walls were covered with a 35mm insulated plasterboard to stop any cold-bridging through the timbers. A few window sills were shaped out of MDF and the room was plaster skimmed. Finally, some skirting boards were fitted and the room was ready for decoration as you see from the final three images. No one would ever know there had been a crisis but the room was left 'reliably' dry and much warmer than it ever was before which will surely be noticed this winter!
There are many reasons why basements may flood, it may be down to extreme weather raising the water table or some type of man-made issue, as was the case for this property (A main water line in the road had burst and pumped thousands of gallons of water into the ground just above the property). Many basements are just damp and it never goes further than that. The problem on this occasion certainly wasn't the owner's fault and really it would be unkind, even churlish to blame the builder retrospectively, as times and methods change and the flood was unforeseen - But, floods nearly always are! So if you are planning a basement, you may have to make economies here and there - but we have to earnestly urge you not to cut corners on your water proofing!
We always ask people to consider, when building or converting a basement or cellar, what could go wrong? Even removing trees can add a huge amount of water to the ground conditions, underground streams can change their course, developers might install new land drainage near to your property which can change everything. It only adds a percentage to a basement construction or conversion to provide a structural waterproofing system and a means of water egress.
This can bring comforting peace of mind after you have completed your basement and spent a lot of money on attractive finishes. Dry basement, dry eyes - wet basement, well...best not go there :o) Thank you for reading.