Hollows in the roof
Just as a broken tile or slate can be removed and replaced with a new one the same principle applies with thatch and hollows in the roof can be made good by inserting more of the same thatch material.
If you have water coming in the key is to obviously try and find out why this is; fixing the leak is the easier part.Often leaks occur around chimneys where the flashings have separated from the stack and water can track between the thatch and the face of the chimney. Another common spot is in valleys where the thatch has rotted or at the top where two ridges meet where there is not enough pitch for the rain to run off. Increasingly we are also finding that leaks near chimneys are the result of porous brick, stone or render and this will often show up as a widespread stain on an upstairs wall.
This is probably the biggest concern that thatch owners contact me with. Is the moss harming the thatch, how do I remove it and how do I stop it coming back? Each roof needs to be looked at on a case by case basis and you can request our moss information sheet by going to our contact page which will tell you more.
Thatch will sometimes slip especially when it is old and does not have wire netting fitted; the usual places are the edges of the roof where very strong winds may cause the thatch to move. Most slippage can be repaired by inserting more fixings to hold the thatch down or fitting wire netting to vulnerable areas but as with moss each roof needs to be looked at on a case by case basis.
Surface patches where the thatch has worn back and is pock-marked
This is when the surface of the thatch appears to be wearing back in some areas whilst the surrounding thatch looks good. The usual way to treat this is to remove all the affected areas and replace with new although if the problem is extensive, there may be a problem with the reed and the only alternative may be to re-thatch.
Ridge pattern work breaking up
Whether your ridge is a butt up, flush or saddled variety if hazel or willow fixings are used to hold it in place these will over time decay and once they do the thatch material underneath whether sedge straw or reed will no longer be held in place and will come loose and break up. There are degrees and stages of this process but anyone who has lived with a thatch roof will appreciate that re-ridging work is a necessary expense.
Lead or mortar flashings breaking up around chimneys and abutments
If the lead is very old it may become detached from the render or brickwork and will need to be re-fixed or new lead put in place when a re-ridge is carried out. This also applies to mortar flashings although if there is water ingress this job will need to be done sooner.
Thatch material being lost
If this is a widespread problem across the roof the thatch may not be packed tightly enough and as with slippage more fixings or wire netting fitted to the roof may be the answer.
Fixings showing just beneath the surface of the thatch
The fixings are horizontal metal or hazel rods which are secured to the roof with screws or thatching nails and if these become exposed it mean the roof has either worn back and will need to be soon re-thatched or that the fixings were not sunk sufficiently low enough under the thatch in the first place.On straw roofs which have more than one coat of thatch the fixings will show up as the heads of twisted spars.
Wire netting not lying flush to the surface of the thatch
Wire netting will over time lie proud of the ridge as the ridge sinks and wears and also especially on straw thatch may also become ‘detached’ from the surface. Wire is put in place to primarily protect the thatch from bird damage but secondly to protect the thatch and if it is not lying flush with the thatch this is not happening. Most thatch owners will address this problem when a re-thatch or re-ridge is carried out.