Gutters are available as insulated or single skin. Clearly the single skin should only be used with external gutters and of course all internal gutters should now be insulated.

Like Rooflights, gutters are available as factory or site assembled. They can also be constructed with a metal or a membrane on the weather surface.

Here are a few observations :-


The Golden Rule


xxx NEVER allow this !!

xxxA liner sheet should always
xxxdischarge into a gutter or
xxxat least outside of the
xxxbuilding (but still not ideal)


From experience, such errors are often mistaken as gutter leaks causing several wasted visits by a roofing contractor in an attempt to fix the problem.

The picture above is of an external gutter ( hence not insulated ) the soffit sheets were formed over the wall cladding, thus any discharge would enter the building.

There is also a cold bridge detail here which would also add a condensation problem


Standard Steel Gutters

Steel gutters are fine, providing they are installed correctly. Often a contractor will remove the mastic from around a bolt hole to allow easier insertion of the bolt. This is a major error. It is essential that the bolt is forced through the mastic in order that it forms a seal around the thread.


xxxWe are sure that we have all witnessed xxxa gutter joint or tow that constantly
xxxleaks, despite the contractor making
xxxseveral attempts at repair. This
xxxsituation usually results in the
xxxapplication of a specialist sealing paint xxxover the joints. An application that may xxxeven invalidate the gutter warranty, but xxxsees out the contractor's obligations
xxxuntil he is paid.

The bolts should also be fixed from the centre out.

Steel gutters should be coated to maintain a manufacturer's warranty - please check with the supplier


Membrane Lined Gutters

Whilst you read the paragraphs below, remember that the roofing process produces swarf which usually ends up in a workman's boots and screws can also land in the gutter. Now remember that the gutter is usually used as a walkway during construction.

Membrane lined gutters are usually constructed with a white liner internal skin, board insulation and then a membrane bonded onto a metal upper skin. However, some gutters are bonded onto the foam board and we have our obvious concerns over these for the reasons stated in blue above. Once water enters under the membrane frost action can continue the deterioration until water ingress occurs.

Where the membrane is FULLY adhered to a metal backing, this is not such a problem.

Remember the internal liner flashing is rarely sealed.

With site assembled Membrane Lined gutters, the membrane can likewise be laid onto insulation only. It is also possible that swarf and debris can be embedded into the foam before being encapsulated by the membrane.



Minimum Thickness of Membrane

It is recommended that the minimum thickness of membrane is 1.2mm. ( this does not include any fleece or other backing medium.



Design size

Each building will need to be designed individually to establish the correct size of gutter and the number, size and position of down pipes. Geographic Location and gutter category will also have a large part to play.

However, if you are preparing a general indicative sketch, we have on our website an old Nonogram dated back to the days of asbestos. ( When roofing was all brawn and no brain ) . This will provide a guide to the sort of size you may require to indicate on your sketch. But please remember that the method of design has been modified significantly since,

This can be found in our Information section or by clicking here. Gutter Nonogram



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