Problems with builders working on your roof


roof problemsOur Independent Surveyors would be happy to help you and give you advice with regards to roofs, roof problems, roof repairs, roof materials, building surveys, structural reports, engineers reports, specific defects report, structural surveys, home buyers reports or any other property matters then please free phone 0800 298 5424 for a free friendly chat.

Fiddlers on your roof, or what builders do when you can't see what they are doing!

roof problems
Ponding on an Asphalt roof

As Chartered Surveyors we have come across many examples of poor quality workmanship when carrying out structural surveys. This article specifically looks at the problems we see in relation to roofing work. Unfortunately when a roofing job is carried out incorrectly or poorly it will ultimately lead to water getting into the structure. Many times water will enter the structure without being visible for quite some time and can cause damage and deterioration below it. This means it is important that you ensure, when you have roofing work carried out, that it is carried out correctly.

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roof problemsWhat do the circles and ovals mean?

The circles and ovals are a system that we used within our structural surveys and building surveys to highlight problem areas so that you are not left wondering what the problem is.




roof problemsOur sketches

In addition to this if the photographs do not, we believe, explain the problem enough together with our survey report we also add in one of our own sketches such as the example that is shown here.




Some of the problems we have seen over the years

1.  A modern slate roof that has been fixed without any securing pins. The photos below show what this looks like. The home owner was completely unaware of how the work had been carried out. All they knew is that there were leaks inside the property.

roof problems
roof problems

No pins are visible indicating the slates have been masticed in place

Slates held with fixing tingles

2.  The reason you cannot see any pins may well be because it has usually been masticed in place. Here are some photos showing how masticing the slate does not work. As you can see the slates have slipped out and nicely positioned themselves on the flat roof below. In this instance it was lucky that there was a flat roof below to catch them. The amount of mastic that was used was fairly minimal.

roof problems
roof problems

Manmade slates that have been masticed in place.

Close up of where a tile has been masticed in place.

3.  The popular way of repairing slate roofs, if you are not going to take the slates off and re-fix them, is to use a lead tingle. Here we can see one on a manmade slate roof.

roof problems
roof problems

Flashing details

How the slates should be fixed with a tingle

roof problems
Quarried slate roof

Let's talk briefly about why manmade slate roofs are used rather than slate. The main reason is that they are far cheaper. Often a roofer will be able to get a second hand value on a real slate, this would mean a quarried slate, and in the example shown above they may well earn as much by removing the old slates and selling them on as they would from doing the job itself. This is great as long as you know about it and are suitably reimbursed. It is not as great if it is done without your knowledge.


It's all about preparation even when you are using builders/roofers that should know what they are doing.

roof problems
Signs that something is not right - plants growing from the gable end

First of all we mean your preparation!

 Quotations are essential.

You need to get quotations for work on a like for like basis. These should be quotations and not estimates as estimates can change in price whereas a quotation tends to be fixed unless it advises otherwise.





roof problems
Signs that the building job is not right – no mortar in the gable end also known as a verge detail

We have dealt with several problems recently where the initial choice of contractors was based solely on price and not on the work they have carried out previously. The people that were about to use the builders were not aware of any of the builders previous work either in the form of visiting previous jobs, talking to the property owners (how long does it take to make a phone call?) or by seeing photos of their previous work.






roof problems
Sign that the building job is going well – a lead verge to stop wind and rain getting in

You cannot compare quotations if you are comparing apples with pears. You need to be comparing apples with apples whilst making sure the brand of apple is the same! If you obtain three quotes for a specific job and one of these quotes is half the price of the others then this generally means that the contractor is quoting for a completely different job.

Our rule of thumb for quotations is for every thousand pounds spent you should have one page of detailed quotation i.e. a £5,000 quotation should have at least five pages.




What should a quote look like on a large job?

rooof problems
Parapet wall has plants growing out of it. Black tar paint tends to indicate there has been a leak

First of all you need to define large. In our experience this varies from person to person. The best way to decide this is to say that a large job is whatever you consider to be a large job. This may be many hundreds of pounds or it may be several thousands of pounds.

Ideally in a perfect world the quotation should be a very detailed explanation of what work is going to be carried out and to what timescale. Trade Institutes such as the Federation of Master Builders do offer a standard-ish contract but you do need to distinguish between the contract and the quotation. The contract sets out the rules whereas the quotation explains what will be carried out.




roof problems
Firstly felt has been used instead of lead. Secondly it does not sit under the slates enough. It should lap under two courses rather than approximately 100mm as can be seen here.

As we have already mentioned we recommend as a general rule of thumb that a quotation should have at least one page per thousand pounds. On a smaller job we would recommend one page of quotations / explanation of what is going to be carried out by whom and when. It may be worth ensuring that you receive approximately one page per five hundred pounds worth of work.






We couldn't possibly do an article on roofs without talking about flat roofs.

roof problems
Mono-ply roof with a felt edging! Yes it was snowing when we carried out this roof survey!

Over the years materials used in flat roofs have improved considerably to the point where we literally have high performance felt that's elastomeric, meaning that it can cope with movement. However this doesn't mean anything if the flat roof is flat and water sits on it as the water will eventually get into the building.






roof problems
Circular repairs carried out on a fish pond roof

We have also seen the trend of using what is known as a mono-ply roofing system. This is a single sheet of roofing. The best example we have of it as it is commonly known is a fish pond lining. This is very widely used in commercial properties on the hidden flat roofs to a McDonald's fast food restaurant for example or a TGI Friday restaurant.

We have come across some terrible examples of workmanship over the years that have allowed water in or ponding. Often this is on insulation that the rainwater soaks into causing long term damage.


roof problems
roof problems

Traditional Cold deck roof with no insulation

Warm roof with insulation


An example of a project that has gone very wrong

roof problems
Fish pond roofs can look good on a sunny day

Today we were asked to look at a roofing project on a high level property (by high level we mean over three storeys in height) where the roofer/builder did not think for one minute that anyone would ever look at his work. In this case very basic rules were broken. Firstly only one quote was obtained. Secondly the £5,000 quotation was on one page (so not the one page to every thousand pounds) and this literally said that they would repair the roof but did not say exactly what they would be doing or in how long they would be doing it for.




roof problems
Ponding on a felt roof. Although a felt roof is good it still needs to have a fall on it

You may be asking how does such a situation arise? You would be surprised at how often we come across people that just automatically trust builders or have often had them recommended and so trust them.

The largest projects we have seen have had quotations carried out on a few pages for costs in excess of a £100,000. The record to date for a one page quotation is £42,000 although it did relate to other work that was being carried out and for drawings of a kitchen completed by a kitchen designer (even though they were then not employed).



The builder/roofer was so friendly before the job started.

roof problems
Flashing has not been fitted properly

As with any sales person (and remember that's what the builder/roofer is in this case) they are very friendly and keen to please and will say exactly what you want to hear prior to starting work. At the end of the day it is what is actually in the quote that is important.




Arguments about what the builder did and didn't include

roof problems
Flashing detail

The most common argument and disagreements we feel are about the quality of the work. Running a very close second is the argument about what is or what is not included. Some builders can be remarkably accurate with their quotations but remarkably inaccurate with their work.


Sequence of work and timing

roof problems
Basics need to be sorted out such as unblocking drains on flat roofs

This is also a bone of contention as often builders disappear and work seems to be carried out in an illogical manner. This means that sometimes things need to be done several times and can be very frustrating for someone who is watching this happen.




Using your own contractors

By this we mean where you have a builder on a project and you decide to use some of your own known contractors for some of the work. This can cause all sorts of confusion for the builder and we feel should be avoided at all costs where at all possible. The builder will blame your contractors and your contractors will blame the builder.


Demands for money from the builder before any more work is carried out.

This is often known as builder's revenge where part of the way through a project the builder decides he will not carry out any more work unless you pay him more money. We have heard of contractors that have literally had their men standing outside the person's house waiting for them to pay them before they will proceed. We have also seen jobs where workmen have literally walked off leaving materials on the roof or in the garden and have just gone onto another job. Of course once a builder has walked off it is very hard to get them to come back particularly if you have fallen out with them. It is even harder to get another builder to take over when you have had a fall out with a builder as they feel there could be future problems. There is almost a lack of trust before they start.


How do you work with your builder?

Please see the article that we have previously written.


Cowboy builders and cowboy clients!


How do you resolve problems once they have happened ?

Phone us for a friendly chat!


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Builders, Building Problems and Roofs and how a Chartered Surveyor can help



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If you truly do want an independent expert opinion from a Chartered Surveyor, and many of us are also Chartered Builders, with regard to building surveys, structural reports/engineers reports/specific defects report, structural surveys, home buyers reports or any other property matters please contact 0800 298 5424 for a chartered surveyor to give you a call back.

We hope you found the article of use and if you have any experiences that you feel should be added to this article that would benefit others, or you feel that some of the information that we have put is wrong then please do not hesitate to contact us (we are only human).

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