u/Healthy-Attorney2257

I've just purchased a new home, a Victorian terrace (built around 1900, solid brick walls, cellar) and I'm trying to get my head around a damp situation. I'm an amateur at this and have been doing my own research. Any advice would be appreciated.

(pics here https://postimg.cc/gallery/Hn9MXz2/a3c5f7a9 )

I'm not looking to make the cellar a usable space, my main concerns are health and structural integrity.

What a damp-proofing company found:

• Rising damp on the ground floor walls (elevated moisture readings described as "consistent with rising damp") (so living room and a bedroom)
• Cellar ceiling joists showing elevated moisture and visible decay, particularly where embedded in the masonry
• High atmospheric humidity in the cellar affecting the joists even away from wall contact

What they're recommending:

• Chemical DPC injection + replastering to 1 metre height across all affected ground floor walls
• Boron timber treatment to all cellar joists
• Temporarily propping the floor, breaking out masonry pockets, wrapping joist ends in damp-proof membrane, rebuilding
• Mechanical sub-floor ventilation system
• Desiccant dehumidifiers

The quote:

They quoted £16,000–£18,000 plus VAT. I said I wasn't sure I could afford the £21,000 all in (that's the £18k with VAT and membrane included), so they came back and said they could do it for £18,000 including VAT but without the membrane.

Independent survey, possible damp from neighbouring property's defective guttering

A RICS Level 2 survey flagged that the high readings to the rear dining room wall are most likely from the neighbouring property's defective guttering tracking down the party wall, not rising from the ground. The front lounge wall does seem to have a more classic rising damp pattern and the cellar timber decay is clearly real, but it raises the question of whether everything has been treated as one blanket problem when parts of it have different causes.

Where I'm at

I don't want to commit that kind of money if I'm not 100% sure the diagnosis is right. A few specific questions:

❓ The cellar gives direct access to the joists from below, could the timber work be done without lifting the floorboards at all, and would addressing the ventilation and the leak from above be enough without major intervention?

❓ Is chemical DPC injection even the right treatment for an around 1900 solid brick property? From my research it seems like there's real debate about whether it works on this type of wall construction, and whether restoring the blocked cellar ventilation might resolve a lot of the readings on its own first.

❓ For the cellar walls specifically, could damp-proof paint be a simpler alternative to a full membrane system, given it's only ever going to be used for storage?

Is £18k reasonable for this scope? General advice and next steps very welcome. I can provide any more details/ images if need - thanks!