Roofs and flat roofs

What is an upstand on a flat roof, and why does a low one matter?

An upstand is the turned-up edge of the covering where it meets a wall, a kerb or a roof window. If it is too short, split, or buried under paving on a balcony, water can run over the top or behind the skirting. Ponding in the middle of the roof is a separate defect.

Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.

What is the fuller explanation?

Surveyors look at the perimeter because that is where flat roofs often fail, not only in the middle of the sheet. A door threshold that sits almost level with the covering, a skirting that has peeled, or a chase that has let go are visible clues. The surveyor usually cannot see whether the membrane turns up behind a render stop unless it is exposed. RICS does not set a millimetre height in the consumer guide. The report should describe what was seen.

A balcony with pots and decking may hide the upstand completely. That is a limitation, not a pass. Lifting decking is not part of a standard visual survey unless you agreed it. Costs of re-detailing an upstand vary. Ask a flat-roofing contractor who will look at the edge, not only at a patch in the middle.

What should you ask your surveyor?

Could you see the upstands, or were they hidden by decking, render or furniture?
Was water getting in at the edge, or was the comment about ponding in the field of the roof?
What further access would show the turn-up of the membrane?

What are the typical next steps?

Do not relay the whole roof because the middle looks wrinkled, if the surveyor’s concern was the edge. Ask.
Photograph thresholds and skirtings before anyone builds a deck over them.
If you need the edge opened up, agree it before exchange and say who makes good.

Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.

Also asked about this

Is a liquid coating a new upstand?

Only if it was detailed that way. A coat brushed up a wall can split at the joint. The survey has not certified the product.

Does a balcony door that sticks mean the roof has failed?

No. It may be the door. It may be the threshold. Ask which one the surveyor could see.