I am a renter and I enjoy feeding the birds by depositing tidbits of rice on the cement sill of the 60yr+ apartment building. I've repainted the sill before with no problem but now I'd like to deal with the problem of the reappearing mold mostly due to the deep sponge like holds that the sill has. NO holes..less of a problem to maintain. I'd like to do a skim coat on the sill and I'm assuming any cement patch will do but I am also wondering if there is an additive for prevention of mold growth. I'd like to make the skim coat as smooth and slick as possible to avoid further moisture issues. What is the way to achieve the smoothest less gritty finish?
Repairing fresh skim of moldy rough cement window sill.
- Thread starter medusa1569
- Start date
Yes, there are additives that you can mix in with your skim coat to minimize mold reappearing. Products like Zinsser AAA-2, Paint Guard Mold and Mildew defense, and MICROBAN Fungicidal Paint Additive either of which should do the job for you.
To get a smooth finish and avoid grit:
To get a smooth finish and avoid grit:
- Sand lightly with fine‑grit (220–320) ; remove dust with a vacuum and damp cloth.
- Use a high‑quality, fine‑grain primer (e.g., a stain‑blocking, smooth‑finish primer) to seal pores and prevent texture from showing.
- For skim coat, mix the skim coat compound with a small amount of water avoid over‑diluting.
- Apply thin, even coats with a wide‑nap roller ; feather edges to avoid ridges.
- Lightly sand between coats with fine‑grit sandpaper; keep sanding until the surface is perfectly smooth.