Water Penetration Investigations
case studies
House with Water Penetration Through the Roof Tiles
Water penetration can occur in numerous locations for numerous reasons. Sometimes due to damage or deterioration, Sometimes due to poor or incorrect detailing. Sometimes due to poor workmanship (a good detail poorly executed).
The picture (right) shows a roof with a tile removed. Beneath this tile is a reflective foil fabric which is installed to thermally insulate and collect any condensation (water) forming on the underside of the roof tiles.
Generally when this is poorly installed the condensation is minimal or the run off from the reflective foil fabric ends up in the eaves.
Unfortunately here the run off all ended up in a corner of a ceiling resulting in damaged plasterboard and mould growth.
The solution was simple. The reflective foil fabric was modified so it discharged any water it collected above the metal flashing and onto the lower roof.
Picture (2) shows a roof with a tile removed from an valley gutter. Similarly here the detail was also modified so the reflective foil fabric discharged any water it collected into the valley gutter.
This is poor or incorrect detailing, the reflective foil fabric should not have been installed under the metal roofing.
If you are asking yourself why it was done like this in the first place. Then you are asking a very good question, one I am unable to answer. In the country and city where this home was built, the builder needs to be licensed and maintain continuing education credits to retain that license. The specialist subcontracting roofing company must do the same. The building works must be executed under an approved building contract agreement which is then administered by a contract administrator who inspects the work prior to paying progress claims. The home also needs to be certified as inhabitable by a Principal Certifying Authority who also carries out regular inspections.
Possibly in the entire chain of those executing and inspecting the work, no one knew any better.
House with Water Penetration Through Masonry Walls
Water penetration is classified into two groups: 1) Hydrostatic and 2) Hydroscopic. Hydrostatic water is water that comes from above or below due to the force of gravity. Hydroscopic water is water that is soaked up by a porous material acting like a wick.
The two photos (3 & 4) on the left show hydrostatic and hydroscopic water penetration happening in the same location.
This home was built out of hollow concrete blocks and featured the blade walls which broke the roof into small sections giving the house a unique architecture. Unfortunately the builder who built the house simply ran the walls up through the roof and didn't take adequate action to isolate the part of the wall that was above the roof from the parts which were internal walls. This had disastrous consequences as can be seen in the top photo. (photo 3) This is just one example of what was occurring all over the house,
Though not shown here this house also had what appeared to be rising damp. Investigation showed that the damp proof courses in the lower part of the walls were in good condition. The water was entering from above, running down the inside of the blocks and saturating the bottom rows of concrete blocks just above the the damp proof courses.
Restaurant with Water Penetration from Roof and Through Kitchen Floor
Water penetration is also often from an internal source such as a bathroom floor or as shown here on the left, from a commercial kitchen floor.
In this instance it is a failure of a liquid membrane material. It appears to be penetrating around a basin drainage pipe, however the failure could be anywhere in proximity to the drainpipe. The water can track under the membrane and penetrate the concrete floor slab where the hole for the pipe has been placed.
The image to the left and at the bottom of the page is a rusting metal section to a a kitchen roof fan. Interesting thing is the leak appeared in the wall of a stairway and looked very much like damp migrating from a saturated tiled bed in the kitchen floor as noted in the previous paragraph. The water was actually from the roof fan becoming trapped behind the render of the wall and tracking down porous course lines in the brickwork. (See 5, 6, 7).
Restaurant with Water Penetration from Flooding Box Gutters due to Leaf Matter
The roof shown here on the right (8 & 9) is on a restaurant situated in the Royal Botanic Gardens which is surrounded by numerous trees.
As you can see from the photograph the original roof layout had a box gutter that would fill with fallen leaves. This gutter needed to be cleaned out every few days. Inevitably the drains clogged and the gutter overflowed destroying a very elaborated plaster ceiling below. This occurred several times.
The were a number of restrictions on what could be done to rectify the ongoing problem with the roof. The restaurant did not want to stop trading for one. The shape and height of the roof could not be altered was another.
The solution was to remove the box gutter altogether. This was achieved by replacing the metal roof with a double layer torch-on membrane laid on plywood.
The drainage outlets were extended to the height of new roof valley. These now acted as overflows to remove excessive water volume from the valley. The pitch of the valley was altered to direct the water to the eaves gutter where a modified elongated rain-head with a leaf guard was installed.
This effectively made the roof self cleaning. Though it needs to be inspected annually and leaf mulched removed a few times a year to prevent plant life growing on the roof and damaging the membrane.