Damp Proof Course (DPC) Injection Creams
Damp proof injection Porto properties rely on is not a surface paint job — it is a horizontal chemical barrier drilled into the mortar course at 100–150 mm above external ground level. We inject silane-based creams that diffuse through the capillary network and repel groundwater that would otherwise climb 1.0–1.5 m up your walls each winter.
What is included
- Moisture profile survey before drilling
- Mortar-bed identification on granite or brick facades
- 12 mm drill holes at 100–120 mm centres
- Silane/siloxane cream injection to refusal
- Hole sealing with colour-matched mortar
- Replaster specification with salt-retardant render (quoted separately)
Why this matters for your property
Without a continuous DPC, hygroscopic salts remain in the plaster even after cosmetic repainting. Peeling returns within 12–18 months and timber skirting can develop wet rot.
Local expertise across Porto metro
Porto's pre-1940 granite townhouses in Cedofeita and Bonfim often lack any original slate DPC. Injection is the least invasive fix when internal floors must stay intact.
FAQ
Manufacturer data for BBA-certified creams cites 20–30 year performance when installed in sound mortar. We specify products rated for saturated masonry — critical where annual rainfall exceeds 1,200 mm.
Yes. Internal injection along skirting level is standard when external access is blocked by narrow Ribeira lanes or shared party walls.
Allow 4–8 weeks for moisture equilibrium after injection. We provide meter readings so your plasterer does not seal damp behind impermeable cement.
Cream diffuses through mortar joints, not the stone itself. On all-granite rubble walls we map the mortar network first — some Porto facades need angled drilling to hit continuous beds.