ventilation problems

Kafer

Hi,

Have a house that appears to be having ventilation problems in some of the rooms. ie. build up of damp/fungus on the corner of the ceilings.

Have been advised that this is because there is no airflow through the rooms even though we open the windows regularly etc.

What is the best course of action?

Suggestion that has been made is to drill 4" holes in each of the rooms, with a 4 " Waste pipe in the cavity and a grid either side?

Windows are PVS non ventilated.

Thanks

bertebug

you could have a damp house

ttm

There are only a few genuinely damp houses - think I've lived in most of them, mass concrete as an example but they all benefit from ventilation.

If you have a damp proof course and you put some heat into the house the only reason for damp is likely to be condensation and one cause of condensation is lack of ventilation.

Check that there are no boarded up chimneys (unused chimneys need/are ventilation) or covered over vents. It’s an all to common a belief that covering up vents will keep the house warmer. If there are no existing vents then you have to make them.

Is there an extractor fan (timer model) in the bathroom, if not fitting a fan here might solve most of your problems by getting the damp air out every time you use the bathroom. If the kitchen often gets steamy then an extractor fan in the kitchen might also help.

Its not the best solution as its need maintenance (a hole in the wall air vent doesn't need servicing very often) but it is possible to put a ceiling vent in each room effected connected to ducting and a fan that goes to an outlet that can come out just under the roof, this is probably only an easy solution in a bungalow. Even so if you suck air out you still need some vents to let air in.

Nearly forgot; obviously damp air condenses on colder surfaces so if the house insulation is poor or non existent that will exacerbate the problem.

So all in all you need a balance of insulation, ventilation and heat.

Just read your post are the rooms that have the problem normally unused and perhaps unheated, if so we are back to the balance situation.

For what its worth our bathroom has no damp proof course, no heating, is often steamed up after use of the shower and bath and when the tide comes in sometimes floods (LOL but not joking as they say its location location location) however we have never had a damp problem in the bathroom untill the extractor fan broke down a few months back. Within days the room started to smell of damp and felt damp all the time even with the window open repalcing the fan fixed the problem.

Kafer

Thanks for the replies.

The house is a 2 storey, has beed cavity insulation and fibreglass roof insulation.

Rooms that have the problem are ones that are both occupied and unoccupied.

THe extractor in the kitchen is very noisey and doesnt really work so we open the windows when cooking. Still not great and the kitchen steams up but doesnt suffer from mould. An adjoining room does though.

I think I will go ahead with adding vents in each room affected and get a new extractor in the kitchen.

What is the best way of drilling these holes? From outside in or inside out. I have drilled such holes before using a hired drill with a 4" circular bit.

ttm

I'm not sure of the relevant building regulations so you better check with someone that does. In essence you don't want to be damaging the cavity wall insulation or allow water or vermin into the cavity but hiring a 4 inch whole drill is the way I'd go;-) If you are spending out on hiring a drill I'd get some suitable pipe to bridge the cavity that will also takes mesh vents first and then get the drill bit to fit might save hunting to find a non existant size of pipe or more patching up than necessary. Also ask the builders merchants there might be a standard way they can tell you to fit any vent you buy from them. Obvious other checks before drilling are checking for pipes and wiring no good saying you didn't know they were there! I've seen all sorts of avoidable damage and done plenty myself ;-)

You can also see when you drill if you really do have cavity wall insulation. Any chance that room next to the kitchen is on the corner of the house with two cold outside walls and the mould is near the top of the wall in the corner?

Edit - sorry missed the bit about which way around to drill? I'd try and go from the outside to the inside measuring carfully so I knew exactly where I was going to end up but to stop too much stuff dropping into the cavity you might need to go from both sides, with a core drill which I have hardly ever used I think you can drill a pilot hole all the way through with say a long SDS drill first. You might also need to cut part way from the inside to prevent the finish blowing off the wall as the drill bursts through the last few mm of plaster.

Kafer

Great vents are the way to go as agreed.

The room near the kitchen has the mould exactly where you mentioned. We are very hygenic. House is spotless. Its disturbing to see the mould.

I'll drill the pilot holes first to ensure that I have the correct spot. Then start with the circular holes.

Anyone ever use these "Hole Master" crowds?

Cheers.

ttm

Kafer wrote: »

Anyone ever use these "Hole Master" crowds?

Cheers.

yep - my step son was going to work for them in the UK but didn't like the way they worked running equipment till it stopped and needed fixing with no maintenance - perhaps they have changed. I think you might find them expensive and I'm not sure how simpathetic some tradesman are to carpets furnishings etc, if its quicker to make a mess and leave it to someone else to clear up then unfortunatley that is often what happens. Start dimond drilling with water and you will have a mess to clear up, great if you are drilling through 3ft of reinforced concrete but overkill on a blockwork wall? Many builders hire bigger core drills so it saves their costs if you hire yourself and you'll be more careful how much mess you make and you will make some mess ;-)

And you aren't the only house with mould in that spot. The wall is cold and any water vapour will condense on the coldest spot, just simple physics and often an indication that the insulation is not installed corectly (often gaps in the corners where the bats are joined) but not much you can do about that.

Sorry did you mean bead cavit insulation (as in polly pearl or some such) or been cavity insulated as in insulated when built or after building?

Kafer

Cavity pearl bead. Done about 4 years ago on 40 year old house.

At the height that I have to drill and the weight of these drills would I not be better off to go for a hole master. Get them to drill as much as they can from the outside and stand on the inside with the hoover on full suction ??

ttm

So what happens when you drill a hole into the cavity and hit the beads:eek: Are they bonded together in anyway? I have heard stories of the beads coming pouring out but thought that was a tall story. Perhaps someone can put me right on that.

Check what type of drilling system they use. If its a wet system then you need to cover up a bit.

OK googled "drilling a wall with bead insulation" and came up with the answer that these bead insulation systems are supposed to use some form of bonding to prevent the beads from moving :cool:. But was a bit worried as I was working on the computers in a call centre that did Poly Pearl sales a few years back and the samples that they had on desks looked very unbonded and free flowing to me.

As to whether to DIY or not I always DIY as I can't afford to get someone in . I also have a tool fetish so any new job is always a good excuse to buy new tools - even expensive ones, but eBays good for that. If I can buy the tool and do the job cheaper than getting someone in then great excuse to buy the tool. I never hire if I can avoid it and often buy good second hand tools for less than the price of a days hire.

Kafer

An example is that I drilled out a 4" hole after being polly beaded and a few came out but the rest were bonded.

I reckon hiring one of these drills at 30 euro a day that I would need it for about 3 days.

ttm

30 euro a day sounds cheap enough especially if that includes the core drill.

How quickly did it drill?

Take about 20mins each block doing it the cheap way I'd do it - marking out the circle then drilling about 30 - 40 10mm holes close together with an 180mm long SDS drill. Then knocks out easy with a cold chisel cutting between the holes. No way as neat as a core drill but needs must

Kafer

I have done it that way in the past too but the core drill is neater.

10-10-20

I would recommend drilling smaller holes. I have 4" vents in all rooms but I was forced to close off most of them due to excessive loss of heat. Our house is on the end of a row and is very exposed. I also fitted adjustable mesh covers to others so that we keep some control over heat loss.
Maybe go for 2"?

ttm

I know this is not the reason this is being done but I have a feeling that 4inch diameter vents are the standard for building regulations. So might as well do it right. Here the need is for ventilation but what do you do if after puting in 2inch vents (is that a quarter the area of 4 inch) the problem is still there. Easier to reduse the ventilation on a 4 inch vent if that provides to much fresh air.

Mellor

ttm wrote: »

I know this is not the reason this is being done but I have a feeling that 4inch diameter vents are the standard for building regulations. So might as well do it right. Here the need is for ventilation but what do you do if after puting in 2inch vents (is that a quarter the area of 4 inch) the problem is still there. Easier to reduse the ventilation on a 4 inch vent if that provides to much fresh air.

You're right ttm, 100mm pipe is correct. Regs require 6500mm2 (91mm pipe is min if you can find one )
Ventilation is a must, for all the reasons listed above.

Kafer

Well the idea would be to close them at night and open during the day when we are out.

Thanks for the help.