Client: Rental Agency
Our client, a rental agency in Lincoln, tasked Timberwise with surveying one of their properties for problems associated with dampness. This property was a mid-terraced house of solid brick, cavity brick, and external render construction, and was both unoccupied and unfurnished at the time of our inspection. The weather conditions were overcast and wet at the time of the survey.
Challenges
Our internal inspection was partially restricted by the kitchen’s fitted units, tiled walls, fitted floor coverings, and solid floors. Our survey was limited in scope as no external property inspection was requested, with our inspection limited strictly to an internal dampness quotation, as per the client’s request.
There was also hygroscopic salt accumulation, as capillary action had drawn ground moisture into masonry and plaster, leaving soluble salt deposits that actively absorb atmospheric humidity. The bedroom chimney breast had also suffered from severe sulphate contamination originating from historic soot deposits.
We also noted a problem with moisture risks, as condensation risks were found at the wall to floor intersections, threatening plasterwork and timber skirting boards.
Observations
There was a large problem in the property with rising damp. Our internal testing confirmed rising dampness affecting multiple rooms on the ground floor walls, including the kitchen and living room, where plaster and wallpaper was visibly crumbling away and giving a “bubbled” texture to the walls. We used non-destructive conductivity metre readings indicating elevated moisture levels in the walls which requires immediate damp proofing.
There was heavy salt contamination in the property; evaporated groundwater had left a large amount of hygroscopic salt deposits which had essentially embedded themselves into the property’s internal wall fabric and plaster finishes. Soot and sulphate salt contamination had also been recorded on one of the bedroom’s chimney breasts.
Hygroscopic salt deposits are soluble minerals which get left behind in a building’s walls from rising or penetrating damp. They actively absorb any moisture from the air, which makes dry walls feel damp. The moisture accumulates in the wall, leaving behind a salty deposit on the walls (often looking like white “tidal” stripes), bubbles and peels paint, and destroys plaster over time.
Solutions
To give our client a long lasting solution, our team would need to strip away the old plaster and start fresh. We would then have to install a new DPC system to prevent damp from rising, and then we would apply a waterproof slurry to stop any future leaks, before finishing the area by replastering. We outlined a full action plan to the client below.
To prepare the area, our team will tape down protective dust sheets over work area floors and polythene sheeting over any remaining fixtures. We will require the client to source an external contractor to remove any existing floor coverings, skirting boards, wall plaster, radiators and pipework prior to treatment.
We will start by stripping any plaster remnants and wooden plugs from the wall to floor joints, raking out and filling any voids below the DPC level. We will brush off visible efflorescent salt deposits and rake out the masonry joints as required.
For the damp proofing, we will drill mortar joints at pre-determined centres and install a DryTek DPC System to specified walls in accordance with BS 6576 and PCA Code of Practice. We will then inject vertical DPC barriers to prevent lateral moisture abridgement from the adjoining masonry.
To waterproof the area, we will apply a HydraDRY vapour-proof slurry coating to wall-floor intersections up to DPC height to establish a Vapour Barrier Up-stand. We will then seal the gap between the floor slab and the render and plaster margin with a waterproof compound.
To finish the area, we will re-plaster the walls using a 3:1 clean sharp sand (BS 882 Grade M) to Ordinary Portland Cement render incorporating Timberwise salt-retardant render additive gauged 1:40 with water. We will terminate the render and apply a skim coat approximately 50mm above floor level. The bedroom chimney breast will be re-plastered using a strong salt-retardant render or dry lining system to isolate the soot deposits.
Rear surfaces of the new skirting boards and joinery with a fungicide or aluminium primer prior to re-fixing.
We also outlined to the client that they would need to allow the plaster to dry naturally without using forced heating and dehumidifiers, applying temporary water-based matt emulsion paint after 6 weeks and delaying permanent redecoration for 12 months.
Results
We provided the client with a clear roadmap to offer long-term damp control. We proposed forming a continuous horizontal and vertical barrier against capillary rising dampness across the treated walls, injecting a full damp proof course. Our finishing works will help to eliminate salt migration and condensation risks to safeguard future wall plaster and joinery. Our work will come with a 20-year guarantee of damp proofing and long term protection, which includes the DPC installation and slurry treatment.
Do You Want Help with a Damp Solution?
Our dedicated and experienced team in Lincoln are ready to talk to you about your options for property preservation. Don’t hesitate to call us on 0800 288 8660, or you can request a survey online.
