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mchu6am4 04-08-2007 10:03 AM

External wall vents closed off - WHY?
Buying 3bed semi and noticed the cavity wall air vents are closed off (cemented) - anybody got any idea why this could be done?

Is it something to do with cavity wall insulation? (as there is insulation installed - wool)

Thanks, Ash

Sammy 04-08-2007 11:34 AM

Are these the vents for the crawlspace under the house?

mchu6am4 04-08-2007 11:47 AM

Sorry, I don't really understand your question (i'm a layman)- but these vents were about 1 or 2 bricks high off ground level.

Sammy 04-08-2007 12:32 PM

If the house is built on a crawlspace where you have access to underneath the house versus being built on a concrete slab, then you would have crawlspace vents to allow air to circulate under the house to help remove moisture.

A vent maybe eight inches high by twelve inches long spaced every eight to ten feet along the perimeter walls of the house. Normally a few bricks up off the ground as you described.

These are set into the brick facade and may have a mortar ramp around the edges to hold them in place and seal the edges but should not be complelety covered in concrete/mortar.

Manual vents would have a button of some type in the middle to slide open/close the vents for winter/summer. Some have a manual thermostat to auto control the open/close.

mchu6am4 04-08-2007 12:38 PM

Understood, thanks. There is no room(s)/cellar under the house and the ground floor is solid concrete.

However, I cannot understand why the air vents have been quite deliberately closed off - as I said the walls have cavity insulation (would any vents need closing off for this?)


Sammy 04-08-2007 01:14 PM

Thats interesting.... Can you post some pic's of the vents?

concretemasonry 04-08-2007 01:17 PM

External wall vents closed off???
If they are the small vents in the mortar joints, they are actually weeps to allow circulation behind the brick and to allow any moisture out. There should be an air space between the brick and the sheathing. Insulation would be inside the sheathing.

Usually, there are corresponding vent at the top of the wall, but they may be hidden by the soffits.

Often people incorrectly seal the vents thinking they are losing heat. They may have been concerned, with insects but you can insert a screen or similar material to keep out critters.

mchu6am4 04-08-2007 01:18 PM

Unfortunately not as its a house I'm currently buying (went to see it again today and noticed the above).

Its not local either (30miles) - its going to bug me now though there was no mention of this in the full building report by the surveyor. maybe he didn't consider it of any concern.

the size of this 'blocking' off was about the equivalent of two bricks for each vent. I could not see any vents but just looked like bricks were missing and filled with mortar covering the size of about two bricks.


concretemasonry 04-08-2007 01:22 PM

External wall vents closed off???
When you have your pre-purchase home inspection, ask the inspector to look at them and give you an opinion.

A surveyor is only worried about the house being on the right spot and not on someone elses land.

mchu6am4 04-08-2007 01:27 PM


Originally Posted by concretemasonry (Post 40061)
When you have your pre-purchase home inspection, ask the inspector to look at them and give you an opinion.

A surveyor is only worried about the house being on the right spot and not on someone elses land.

What is this pre-purchase inspection, who does it (I'm a FTB) and does it cost any money ? When is it carried out as the house is going through the purchase through the solicitors.


Sammy 04-08-2007 02:23 PM

The home inspection is optional and paid for by the buyer [you]

Cost varies but maybe 200-500 dollars.

It is arrainged by you and you get to pick the company. Your real estate agent can probably recommend a few companines to select from. You can even be there if you wish and go thru the thouse with the inpsector. In any case mention the issue you have with the vents. A good home inspector will give you a written report of all the conditions at the end of the inspection.

Being a FTB I would strongly suggest it and evaluate going forward with the purchase only after reading and understanding the inspectors report. Its well worth the money to make sure you dont get stuck with a lemon.

mchu6am4 04-08-2007 02:41 PM

when you mention dollars, it seems like this is something you do in US? I am based in UK and had a full building survey done (which I would think is your equivalent)

Sammy 04-08-2007 02:44 PM

Yes I would be speaking of U.S.

If your in the U.K. I would check with the person who did the building survey and see if they can can answer your question on the vents.

concretemasonry 04-08-2007 03:27 PM

Sorry, I just assumed you were in the U.S.

Since you are in the U.K., you may have a different wall cross-section with no wood or sheathing. If it is the double 3" or 4" masonry wall my comments may not apply.


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