Dampness in building elements

Desktop research

• Desktop research of local geology, soil conditions, watercourses, etc. Remember that specialist geotechnical surveys may be required.
• Make enquiries to local building inspector regarding basement tanking systems used locally and their performance.
• Are there any specifications for tanking, any guarantees?
• Have any building repairs or improvements been undertaken to affect basement moisture conditions?

Site

• Assess site conditions, ground levels, soil type and water table.
• Assess relationship between external ground levels and internal floor levels to establish walls that are below ground.
• Plot position of underground drainage or water supply in relation to the basement, and any ponds, streams or other water sources.
• Leaking underground potable water main supply pipes – check with the local water provider, if any escapes of water have been reported or investigated locally.
• Note position of any potential dampness threats above ground – leaking rainwater goods, poor detailing, etc.
• Is there any history of flooding in the basement next door?
• Is there a regional history of flooding – check historic news reports for the area and also the Environment Agency web site and/or National Rivers Authority of Local Authority or District Council.

Construction

• Which walls are earth retaining?
• Has the basement been tanked (i.e. waterproof box) or partially waterproofed (structural waterproofing)?
• Are there any sumps with pumps installed?
• Have the basement walls been tanked externally or internally?
• How has the original construction been compromised or modified?
• Are there are particular difficulties of detailing at services entries etc?
• Are there any cracks to a structural waterproofing/tanking system?

Look carefully:

• Are the cracks hairline/superficial – or structural/movement cracks?
• Is there evidence of progressive movement?
• Can a cracked, damaged or ineffective waterproofing system be repaired by a traditional or patent method?

Symptoms/causes of dampness problems

• Are there any obvious or localised areas of dampness?
• Are there any possible reasons for localised dampness?
• Where a basement has been partially waterproofed, moisture may track round the waterproofed section to cause problems adjacent – laterally, below or above.
• Does dampness or water pooling occur at particular times, intervals or seasons?
• Are there signs of mould growth or timber decay?
• What is the condition and nature of finished or substrate?
• If there is a guarantee for a waterproofing system, is there an attempt to only guarantee the system against 1 or 2 moisture sources?