Concrete Finlock Gutters — Relining and Sealing Daniel's Roof

1) Sealing

This option is best suited to DIY as it requires no specialist tools and is also commonly used by handymen and general roofing contractors.

Here is what you need to do:

  • Remove all debris from gutter and allow to dry
  • Wire brush inside of gutter to remove any existing flaky sealant
  • Fill any gaps inside gutter with fast setting cement
  • Coat inside of gutter with an acrylic roof sealant see right of page
  • Apply a thick coat of sealant or two average coats
  • AVOID cheap alternatives such as Bitumen as they have a shorter life expectancy

This method is by far the cheapest and if done correctly should last 6-10 years, after which it will need to be repeated. This work can be completed by DIY or handyman but please note that you may need to remove the first course of roof tiles so access to the gutter can be achieved.

2) Gutter Liners

Another popular method is to secure a liner to the inside of the concrete gutter. There are three types of gutter liner available rubber. aluminium and torch on felt (similar to what is used on flat roofs such as garages).

This type of work needs to carried out by specialist roofing contractors and extra care must be taken when lining the gutter. If your property is a semi detached or in a terrace and your gutter is shared with a neighbour then please be advised, it is best to have all neighbouring concrete gutters lined at the same time. If neighbouring gutters are not lined a seal will need to be created on the boundary and this is a common weak spot in the system and known to cause leaks.

The life expectancy of torch on felt is over 15 years and for both the aluminium and rubber liners its in excess of 20 years, assuming the work has been done to a high standard.

3) Removal of Concrete Gutters

It is possible to completely remove the concrete gutter blocks and replace them with a more attractive and leak resistant alternative such as Upvc or aluminium.

Although this may seem a drastic step, it is worth considering especially if your property is detached. The work usually involves cutting the blocks and then securing a timber or plastic fascia board to which the new traditional guttering can be secured to.

If the property is semi detached or terrace then it would be best to replace all the blocks but if that is not acceptable to the neighbours then the blocks can be capped off at the end, see photo.

Photo courtesy of TLG Guttering (opens in new window)

Why Concrete Gutters Leak

The design of concrete Finlock guttering is flawed. Concrete itself is heavy and water permeable. They were initially used during the second world war as other materials such as metal were sparsely available. Concrete guttering was never designed or used because of any advantage They are for many people a nightmare aspect of their home.

The main problems of these gutters are outlined below:

  • 1) Heavy concrete will suffer frequent movement and cracking of the joints
  • 2) Sealant used on the inside of the gutter is also subject to cracking caused by movement
  • 3) The guttering is often only a few inches from the ceiling a leak can cause considerable damage
  • 4) Finding the specific location of a leak is sometimes impossible leading to expensive repairs
  • 5) Unlike normal gutters repairs need to be carried out by specialist guttering companies


Related Products

Here is a list of other products you may wish to consider as well:

Gutter Hedgehog – This is a brush like product that is laid into the gutter, it is manufactured in 4 metre lengths and can removed and re-installed very easily.

Gutter Foam – This product doesn’t work as well as  I initially expected. Here is my experience of this product and why I will never use it again.

Gutter Grid This is similar to the Gutter Mesh but is far more rigid, it won’t collapse into the gutter but does have large holes that catch pine needles.

Downpipe Filter This filter only costs a few £s buy will prevent costly blockages in the underground pipework. Use with or without gutter guards.


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