Mould behind kitchen cabinets 👽

azk404 · Post by **azk404** » Fri Dec 08, 2023 10:55 pm

After a long work week I sat down in the kitchen looking forward to the weekend only to notice some mould on the kitchen toe kick and further discovered mostly green mould all at the back of a corner cabinet, as well as some dusting on the bottom insides of various other cabinets as well as other spots. The worst hit spot seemed to have some shiny water droplet type mould that seemed very alien.

There goes my relaxing weekend

as I will mould spray and remove as much a possible, fog spray it (sanigone), then install some 50mm round vents around the sides/backs (nothing in the doors though) as-well as a toe kick vent to try and give it some air flow.

The corner part is against an external wall but I didn’t have this issue last year so what other issues could it be and any other remedies I can try out to help control it? I did have a leak from the sink about 6 months ago which caused a large puddle but I dried it up quickly, although maybe it spread more thank I thought.

There is also traces around under the cabinets and as said light dusting inside other cabinets on the bottom.

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big-all · Post by **big-all** » Sat Dec 09, 2023 2:10 am

general thoughts any changes at all
like new drying regime or more moisture generation like drying clothes in a new way 'new tumble dryer ' opening shower /bathroom door after use
any building /sealing work ventilation or insulation wise
any change in heating style like bottled gas or parafin use
any changes the other side off the effected area like driving rain or build up like soil or planters

but in general such strait line suggest outside in via a defect at that level in walls /batten internally or outside with the easiest route directing to that point :dunno:

if you push the back does it give quite a bit perhaps 6mm or not at all suggesting physical contact between cabinet and wall :dunno:

azk404 · Post by **azk404** » Sat Dec 09, 2023 9:55 am

No changes, other than the tap leaking that time.

Last winter we dried cloths inside with no issues and this winter we actually use a dehumidifier when we do.

dewaltdisney · Post by **dewaltdisney** » Sat Dec 09, 2023 10:54 am

The causes of mould in these situations invariably point to cold spots, humidity, and mould spores. It is difficult to track mould spores as they can be carried in by the breeze, or be carried in by clothes and shoes. Mould needs dampness to grow, it draws nutrients from carbon, oxygen and water. Your issue seems to point at a cold spot and moisture in the air will condense on a cold surface to provide the dampness that will allow the spore to germinate. I would think that your proposed clean will kill off what is present and you may have to look at perhaps putting some insulation behind to prevent the cold spots.

I had an old tractor and I suffered a blocked fuel filter. On examination I had a black sludge develop in the tank. Condensation had run down the fuel tank walls and water being heavier than diesel it formed a shallow level at the bottom of the tank. Mould grew in the interface drawing carbons from the oil and oxygen as well as water from below. So it just shows that mould will grow anywhere that presents the opportunity.

DWD

Neelix · Post by **Neelix** » Sat Dec 09, 2023 1:08 pm

Where is the sink, washing machine, dishwasher?

Do you have a leak?

azk404 · Post by **azk404** » Sat Dec 09, 2023 2:38 pm

I was planning to make some vents at the back of the cabinets but after cutting a large hole in the 3mm MDF Ikea back panel there was green mould on the wood and it feels like it’s absorbed moisture. On the right line of cabinets of the L kitchen the back was very close to the wall so I have now just removed all the back panels to find them all having mould. The worst hit area was the corner and the one to the right of it. One more cabinet to the right is the sink which wasn’t too bad but still had some mould and then one to the left of the corner which holds the oven had some but not as bad as the corner and cabinet just to the right of it.

The majority of the mould was on the MDF wood backs rather than the wall so what does that say? Although, there was a bit of the wall but the panels were warped and touching the wall also.

- I have a couple things I’m planning, remove all the 3mm backings and clear away all the mould of course.
- Ived drilled some 60mm vent holes in the sides of the cabinets.
- is it wise to drill some holes at the bottom back corners to let air flow from the plinth vents up and out?
- I think I will leave the backs off for now and then pain the walls with aint mould paint. How would I go about insulating the area without removing the cabinets? Rockwool against the wall then build some moisture resistant backs on top of that?

Other than what’s mentioned there’s been no changes.

Sink and dish washer position below.

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dewaltdisney · Post by **dewaltdisney** » Sat Dec 09, 2023 3:04 pm

It looks like there might be a damp issue. Check outside for a bridged damp course or any defective guttering. The mould was on the board as it fed on the carbons in the MDF. I would advise pulling the units out, you should be able to unscrew them leaving the worktop in place. You need to get in to sort the wall problem.

DWD

azk404 · Post by **azk404** » Sat Dec 09, 2023 8:31 pm

The way the kitchen and top is put together it will be a huge pain to remove the cabinets. Mainly as the stone top is resting on the cabinets and attached with mastic.

I will inspect the exterior wall tomorrow and if I do find a hole or crack that could be allowing moisture in then fill it, could the brick work dry over time?

Neelix · Post by **Neelix** » Sat Dec 09, 2023 9:03 pm

How high is the DPC above the patio?

big-all · Post by **big-all** » Sun Dec 10, 2023 12:35 am

general comments,
a shiny surface will not allow moisture to be absorbed, so will collect so moisture attracted from the cabinet back will just fester in the back and appear at the front when the shiny surface delaminates allowing it to show through
in general this is why unfinished surfaces that can breathe will be the last to propagate mould as moisture will be shared around back and forth

azk404 · Post by **azk404** » Fri Dec 15, 2023 11:37 pm

Hello

Ive had a free assessment done by a company called Kenwood (which also do contracting) and the verdict from the dude was that its mainly due to humidity in the air and the temperature differential within the house and not a rising damp or leak somewhere. The corner of the kitchen is against an external wall and with a little temp gauge inside the cuboard its reading 14* even though just outside the door is 20*. I am also getting a humidity reading inside the cupboard of 90%

but outside its 60-64%.

He said because there was actual black/green mould its probably not external water as the inside moisture is contaminated which leads to mould growing but external ground water has salts which wouldn't (or maybe not as quickly?)... Any thoughts on that? I have used a dehumidifier inside the cupboard and it looks like the damp patches have gone if thats a sign it was just moisture accumulating from inside humidity behind the backings.

Could be wise to get a 2nd paid for analysis done though which I think I will do.

Although if its the same results what to do... Plaster board with insulation? Although removing the cabinets will be, well I'm not sure its even possible without ripping it apart. Get a humidity fan in the kitchen? But will this help with the inside of the cupboards?

A

azk404 · Post by **azk404** » Sat Dec 16, 2023 12:01 am

Injection foam insulation?

big-all · Post by **big-all** » Sat Dec 16, 2023 1:31 am

foam insulation is not a good idea if it traps moisture in as you will just get sweat and drips
if its just a cold surface rather than a damp surface then perhaps a thin polystyrene veneer on the cupboard outside back but with an airgap off at least 12mm between wall and veneer :dunno:

azk404 · Post by **azk404** » Sat Dec 16, 2023 9:02 am

When you say traps moisture in do you mean moisture thats already absorbed into the walls or general moisture in the air?

With the polystyrene idea would the exterior wall still be cold and eventually when warm air gets behind the back it will condense over time?

dewaltdisney · Post by **dewaltdisney** » Sat Dec 16, 2023 9:18 am

You need to find out why the wall is damp, have you checked outside yet. The dampness in your photos is indicative of a damp course breach.Check the level outside to see if the soil level or slabs are higher than the damp course. That is not airborne moisture condensing on a cold spot.

DWD