Roofs and flat roofs

Does a plastic gutter mean the old cast-iron one has been properly replaced?

It means someone fitted plastic where you can see it. It does not mean the falls are right, the outlets are sized, or the hidden brackets are sound. Cast iron can still be doing the job if it is painted and jointed. A home survey sees rust, leaks and sagging. It does not certify either material, and it does not require you to replace cast iron because it is old.

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?

Old cast-iron goods are heavy. When brackets fail, the gutter tips and soaks the wall. Plastic splits and pulls out of clips. The defect is the leak or the fall, not the fashion. A surveyor on the ground cannot always see the back of the gutter. They should say if the comment is from staining on the wall rather than from a hand on the joint.

Listed buildings may control the material. The survey does not grant consent to swap cast iron for plastic. Ask the solicitor if the front is listed or in a conservation area before you accept a plastic quote. There is no RICS price for either material.

What should you ask your surveyor?

Is the gutter leaking, or only old?
Could you see the brackets and the fall?
Is there a consent constraint on changing the material?

What are the typical next steps?

Repair what leaks. Do not replace a sound run because a brochure prefers plastic.
If the house is listed, check consent before you change material.
Ask the roofer to include outlets and brackets, not only the length of trough.

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 asbestos cement gutterware the same as cast iron?

No. Cement goods on a pre-2000 house can contain asbestos. Do not break them to “check”. That is an HSE question, not a style question.

Does new plastic prove the fascias are sound?

No. The board behind a new gutter can already be soft.