In our regular monthly column – ‘An Inspector calls’ – Total Contractor has teamed up with the experts at BMI UK & Ireland, leaders in pitched and flat roofing solutions, to help you avoid the common pitfalls that can often cost you both time and money and ultimately help you achieve roofing success.
This month the Inspector nails down the question of repairing ridge or hip tiles.
It’s a pretty common sight on roofs across the UK; ridge tiles, as shown in the image (left), that have effectively lost all the mortar bedding – front, bottom, back (no doubt) and sides. Consequently, it’s only a matter of time before one or more departs the roof and makes its way down to the ground in a damaging and potentially injurious – even lethal – way.
Repairing a bedded ridge or hip tile such as this is one of the most common minor repairs undertaken on a pitched roof, and prior to 2014 the solution was a simple one. Remove the tile, clear the old mortar before mixing new and re-bedding the fitting alongside its counterparts. Job done!
However, all that changed with the introduction a few years ago of BS 5534:2014 the Code of Practice for Slating and Tiling in the UK and then subsequently the amended version BS 5534:2014 +A2:2018. It applies to all pitched roofing, whether new build, re-roofing or repair work, and although not legally mandatory, compliance with it is considered not only best practice, but also provides the best defence in the event of failures or disputes.
The revised code of practice states that the use of mortar alone can no longer be relied on as a method of fixing, as it has been deemed to provide no reliable adhesion. Mortar can still be used but only if accompanied by mechanical fixings. This means if mortar is used then additional materials are needed including a ridge/hip batten with fixings to rafters, and mechanical fixings for securing the ridge/hip tiles to the ridge/hip batten.
Worst case scenario is that the tile may fail and cause injury or damage when it drops from the roof
Remove the risk
While the above secures the ridge/hip tiles it does not eliminate the risk of mortar failure, resulting in roof leakage and subsequent repair work as the mortar can still crack and drop out of the mortar bed. A simple way of avoiding all the hassle associated with mortar is to use the alternative of modern dry-fix ridge/hip solutions instead.
So now we need to consider how we secure a ridge batten beneath the pre-existing tiles to achieve the mechanical fix, which inevitably leads us to the stripping of more ridge tiles. In fact, the argument for replacing the entire ridge is now quite compelling given that the visible degradation of this one tile will most likely be followed with the failure of the rest. Why waste money making multiple minor repairs when you can strip and re-fix in one go?
Either way, a supporting timber must be installed, and a mechanical fix or dry fix system must be employed to properly secure the tile. If not, then worst-case scenario is that the tile may fail and cause injury or damage when it drops from the roof. This situation is not as rare as you might think and the consequences for the roofer could be quite severe, so it’s well worth brushing up on your standards and ditching that old reliance on mortar.