Drilling through wall to fit vents. PICS

[EddieJT]

I want to rid a flat of condensation by fitting vents to the walls.

My first preference would be one of these

but then I'd need a 127mm core drill which is gonna cost me £50 (unless I hire one).

So I'm also considering a these

. They are the cheaper option and I wouldn't need a core drill. I'm thinking of drilling many 10 x 16mm holes through the cavity wall and then cover the holes with the above vent.

Is this a good plan, or am I missing something?

Thanks in advance.

 

[BigIan]

G`day Eddie,

The fitting of vents to get rid of condensation is a plan that works and works well. and to be honest the type of vent you fit in this situation is often simply a matter of asthetics.
You do also need to be aware that the fitting of a vent will also allow your lovely warm air to escape from your house so your vent need only be big enough to remove enough of the warm air to get rid of the condensation. and there may be other methods of curing the condensation (additional insulation for instance) even simply repairing your pointing can prevent air leakage causing cold spots & condensation. also upgrading the extraction to areas such as kitchens and bathrooms will be of great use.

If you are set on fixing a vent, Then you can drill several holes using a long bit through the entire wall, and break these out with a hammer and chissel and re point after (I`ve done it many times and hate it but the cost of core bits is silly)

Hope that hasnt confused you too much?

 

[EddieJT]

Great, thanks for the explanation and confirmation Ian.

You mention knocking out the brickwork after drilling; am I being paranoid, but is it not detrimental to the structure of the walls to be knocking out potentially 6" x 9" hole?

 

[BigIan]

I`m sorry I must have miss read what you were planning, I assumed you were going to fit a duct (pipe) through this hole an so you would be looking at making a hole roughly 150mm dia?

if this is the case I would mark where I want my duct to go including the outline, I then drill lots of holes along the circumfrence of the circle to "perforate" the masonry then knock this out.

as to your other plan of drilling many holes and fitting the grill over it, the issue with this is that you are then allowing warm moist air into the cavity which could lead to further damp issues any penetration through a cavity wall needs to be ducted and sealed to prevent this.

 

[EddieJT]

Ah, ok, well I'll go with the ducting then, thanks. Glad I asked now.

 

[dishman]

I would just add that only improving insulation whilst not having any ventilation or thinking about ventilation can often make condensation worse....

This is because with better insulation and no ventilation, more warm moist air is trapped for longer in the property. There will always be some areas you can't insulate well in an old property, and you may get cold spots on external walls.....as a result the moist air will be more likely to condensate on the cold spots (or the coldest areas, windows etc) you can't insulate, and hence you get concentrated damp in these areas.....

Back to the initial post, you did not say where you were putting these vents....firstly, if it is the kitchen and bathroom, I would always put an active (mechanical) vent in here with a humidistat.

A lot of moisture is created very quickly in these rooms and needs to be removed just as quick, a passive vent will not cope with this...

Passive vents are good for background ventilation, not as much air passes through these as one would think, but they are good at their job.

However....if you are worried about losing heat through ventilation you can look at special extractor fans which also recover the heat back into the room. They are called single room MVHR.....

http://www.vent-axia.com/range/hr25.html

....they are more expensive but ventilate without as much heat loss......you need to work of if this is worth it based on how well your house is already insulated.....

Whatever your choice, just ensure the minimum you get is a mechanical extractor in the bathroom/kitchen with a humidistat. (a humidistat keeps the fan going until a selected acceptable humidity is reached).

 

[BigIan]

I would just add that only improving insulation whilst not having any ventilation or thinking about ventilation can often make condensation worse....
[/quote]

I would argue that point.

Condensation will only occour on a surface where the temp is bellow that required for the air to retain moisture.
The instalation of improved insulation in areas that suffer from condensation create a warmer surface internally preventing condensation from forming.

This is because with better insulation and no ventilation, more warm moist air is trapped for longer in the property.
This would be true if you were retrofitting an entire building and improving the air tightness. however the improvement of the insulation stratagy for a single area providing properly specified would still leave adequate air passage through the rest of the building.

 

[dishman]

You are correct, insulating may present a warmer surface and in turn may prevent condensation from forming on that surface.....

......But the moisture is still in the air, it is not going anywhere (especially if you remove ventilation). Whilst this may dissipate overtime ("trapped for longer") through the house, the chances are the air will cool enough to condensate somewhere else, especially windows (even if they are dg upvc), or cold spots on walls in other areas of the house....

When creating huge amounts of moisture in places such as bathroom, it should be removed as close to the source as possible....

 

[EddieJT]

Well to put you in the picture, this is a flat I rent out. It's a 1960s 2 bed ground floor flat with double glazing and GCH. I used to live there myself and often had the windows ajar and rarely used the heating (cheapskate), and never had a problem with condensation.

Now I've got tenants in there who have the heating on like there's no tomorrow and never open the windows! As a result there is bad condensation and mould all over the flat.

 

[dishman]

That makes perfect sense....You have the windows ajar, the house is well ventilated, if it is not that large and you are not producing much water vapor, then you must have decent air circulation and it gets vented quickly enough for the way you live and the type of property you are in....

With your renters.....it seems they are doing all the wrong things. Poor heating control, creating lots of humidity with no ventilation (shut windows) which is exactly the scenario I was alluding to...

They are probably creating a lot of water vapor (drying clothes on radiators is the worst). Warm air holds much more water vapour than cold air (which is usually good as it has time to ventillate), but if there is no ventillation, it wont circulate out and as soon as the warm air touches a colder surface it cools and condensates. To make matters worse, if the heating was on quite high and then goes off at night or part way through the day, the air cools and therefore cannot hold all the water vapour so even more condensates on any "colder surfaces". Therefore you get loads of condensation. This is why damp is a problem associated with winter, because the cold surfaces are that much colder, so the air cools quicker, hence more condensation...

If they do not understand that they are creating the problem, then you get it across to them somehow.....

The solution is, changing how they use the property (habits), more ventilation (especially in areas prone to creating water vapour), and better heating control (avoid lots of heating and cooling).

Read these recent posts:

//www.diynot.com/forums/building/is-this-damp-how-can-i-get-rid-of-it-pics-inside.390150/

//www.diynot.com/forums/building/low-level-damp-patches-on-internal-walls.389770/

and these (maybe print off a copy of these for your tenants):

http://www.bolton.gov.uk/sites/DocumentCentre/Documents/Condensation and Mould.pdf

http://www.scotland.gov.uk/Publications/2005/05/10103020/30217

 

[dishman]

Posting error- whoopse

 

[EddieJT]

Those documents are perfect, I'll send them to the tenants to reinforce the point.

Before I jump in drilling 5" holes into the walls, I might have a meeting with them and get them to change their habits.

 

[dishman]

I would at least recommend a good extractor (with humidistat) in the bathroom. And if there is not an externally extracting cooker hood in the kitchen, maybe one in there too.

Also ensure that they do not dry clothes on radiators (if that is something they are doing), it is a common issue in rented properties where tenants do not want to use the tumble dryer as it is viewed as expensive.

If they do not have a tumble dryer, maybe invest in one as a landlord, but the vented kind rather than condensing. Or ask them to use a launderette. You may want to write in a future contract not to dry clothes on the radiators (hard to enforce though).

Finally, I don't know if your flat is freehold or lease hold. If you are leasehold you may need to contact your freeholder and get their consent to put vents in as it affects the external walls of the property. It will say in your lease if you need to make them aware...I don't see why they would say no as it benefits the property