Age and type of house
A 1950s trussed-rafter roof carries a water tank the trusses may not have been laid out to hold. What should the rating not assume?
The rating should not assume those trusses were laid out to carry that tank. A 1950s trussed-rafter roof is a set of light timber frames, and a water tank may load a point they were not arranged to hold. The surveyor can see the tank, the boarding and any sag or stain within reach. They do not calculate the truss. The tank and pipes were not pressure-tested. A loft is entered only where the hatch is safe and not more than 3 metres up.
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?
Trussed rafters work as a series of small frames. They are easily weakened by cuts, and a heavy tank on a few ceiling ties can bend the very members that should stay in shape. The survey can record a sag, a cracked plasterboard below, a tank sitting on ceiling joists, or a platform that looks added. It cannot produce an engineer's load figure, and it should not pretend a lack of dramatic sag means the layout was designed for the weight. Water services are visual only. A full tank on the day is not a test of the ball valve.
If the loft was not entered because the hatch was high or unsafe, the tank itself may be NI, not inspected, and the rating must not quietly assume the roof is fine. Ask whether the trusses have been cut around the tank and whether the support is a proper platform or just the ceiling. Do not remove the tank before you own the house. If the ceiling below is cracking under it, that is the observation to put in front of a structural person, separate from a plumber's quote for the cylinder.
What should you ask your surveyor?
- Did you enter this loft, and was the tank support fully visible?
- Are any trusses cut, notched or sitting under the tank without a platform?
- Is your rating refusing to assume the roof was designed for this load?
What are the typical next steps?
- Do not treat a quiet ceiling as proof the trusses were designed for the tank.
- If the hatch was not entered, keep that limit on the front of your decision.
- Ask a structural person about the platform if the report flags the load.
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 every tank in a trussed roof a defect?
No. Some are properly supported. The point is that the rating must not assume the layout was designed for the weight without looking.
Were the pipes tested?
No. Services are visual only. A tank seen from the hatch is not a plumbing test, and a closed hatch is not a view at all.