waterproof existing floor

Old 12-27-22, 01:28 PM
Thread Starter
Join Date: Dec 2022
Posts: 1
Upvotes: 0
Received 0 Upvotes on 0 Posts
waterproof existing floor

moved into this house 2 years ago, we just had water leaked from porch floor into part of bedroom ceiling. we are in rainy area and depend on winds, the porch floor get water a lot. water seems came in along one of the joist and soaked the rest of drywall panel, I opened up a big area, no visible water, musky, high moisture, been running dehumidifier.

need help with
1. how can I determine if waterproofing was done before the ceramic tiles on the porch
2. i see one of the floor area sank lower than the rest and water can stuck in there. i suspect these water leaked through the grouts?
3. without redo the flooring, any suggestions on what I can implement for waterproofing the floor and ceiling?

thank you!

picture#1: ceiling opening
picture #2/3: upstairs porch floor, ceramic and sanded grout. i haven't done any seal since moved in.
Old 12-27-22, 03:03 PM
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 28,329
Received 2,311 Upvotes on 2,056 Posts
"...and depend on winds"
Is this important information? Do you think water is being blown underneath siding or trim, or being blown around a door or window and causing the leak?

1. If it hasn't leaked in two years there is probably a waterproofing membrane or other waterproofing but has developed a leak.

2. Yes, water flows downhill and will collect in low areas and keep trying to find a way to keep going (leak). Grout is not waterproof. It is there to fill in the gap between tiles. If it is in perfect condition it can keep bulk water out like from a sudden shower. It is not waterproof and if wet for a long time water will slowly seep through it even if it's not cracked. If the grout is cracked then the water can get through even easier.

3. Stop thinking of that area as a "floor" and call it a "roof". It needs to be waterproofed like a roof. If that is where water is entering the tile will need to be removed and covered much like a flat roof building. Then a deck or patio could be built on top. There is no paint on product or grout sealer that will work long term. Some things can be applied as a temporary "emergency" patch but it is not permenant.

I am highly suspect (do not trust) how that area was waterproofed. Tile over a wooden roof is unusual and needs pretty specific construction to keep the water out permanently.

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: