We are getting a property we have just bought ready for rental, and there is damp showing on the wall by the chimney. We know it comes from above, so we called a roofer.

From the outside the roof looks okay. The tiles are there, nothing is hanging off. But when the roofer went up and filmed it, you could see that the underfelt was damaged, with a hole in it. The gutters need cleaning as well, but the felt is the real problem.

What the underfelt actually does

Most of the time, the rain comes down the tiles, into the gutter and away from the property, and the underfelt is not really doing much. It earns its keep the day a tile cracks. Some of the water comes in, lands on the felt, and the felt directs it down to the gutter.

Now take the same cracked tile with no underfelt. The water reaches the timbers that hold the roof and the loft ceiling, and then the bricks, which are like a sponge. They absorb the water and it damages the paint, the plasterboard, everything. Water is one of the worst enemies of your property.

The felt we would put back is the breathable kind. It lets water vapour escape but does not let water in, so the house can breathe and still stays dry.

£780, and a £170 fee nobody mentioned

The first quote to fix it is £780, which is quite a lot, so we are getting other quotes to compare.

The part that has never happened to me before is the call-out fee. We have many roofers who come and check and do not charge for it, and I do not mind a fee as long as we are told in advance. This one charged £170, in Merseyside, and told us afterwards that the fee is on his website. I did not get his phone number from a website. I got it from somewhere else, so I am disputing it.

Having said that, if the job is well done and we have a quality roofer, I do not mind paying, because of the problems this avoids now and in the long term. So ask about a call-out fee before anyone climbs a ladder.

Why this matters to an investor

You do not need to be an expert in roofs. But you do need to understand the basics of how your building works, because a simple piece of fabric, to put it bluntly, keeps you and your tenants dry and comfortable and protects your investment, and it is such a tiny part of the house.

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