Damp, Air Vent and Chimney.... Ooh what fun! All manner of questions and solutions to problems and issues surrounding the subject of brickwork, blockwork and stonework

[pyramid]

Hi all,
I have recently purchased a property which has a number of problems.
Firstly there is [color=red]damp in the front room[/color] running across the wall facing the outside. In the middle of the wall is the window, directly below the window under floorboards is the original air vent. just below the window and to the right is a mess of plug sockets, the brickwork here has, by the looks of things, been been hammered out to make a hole for the socket, [color=red]newspaper has then been stuffed into the hole around the socket then a mess off cement applied[/color]. I believe this to be one source (probably the original source, oh yes there is more) of where the damp is getting in. Just below the window and to the left above the skirting is an [color=green]air vent [/color](my theory being that when the electricians bridged the cavity wall and created a route for the damp that another cowboy firm were called in and missed the cause for damp or ignored it and added the vent for some easy cash! The air vent hasnt been fitted well at all, in fact I have already pulled it out with a view to bricking it back up or I might install a better air vent depending on the responses I get here, bearing in mind that all the [color=indigo]cavity wall insulation around the air vent is soaking wet[/color]! So there we have a possible two sources of damp. I have knocked the plaster of exposing the brickwork to about 1.5 mtrs from the floorboards, the rotten skirting and first 3 boards from the skirting. ANY helpful comments and advice would be greatly appreciated. And on an easier project I am blocking a fireplace, do i have to use brick or can i dot and dab plasterboard to the surrounding brickwork? and does it need an air vent? and if you have read all the way to here thankyou :)
I have photo's on photobucket - hopefully this link works - http://s699.photobucket.com/albums/vv35 ... salisbury/ - you might have to copy and paste!

[stoneyboy]

pyramid,
You will need to gain access to the areas where holes have been made through the wall so that you can remove any rubble which is sitting in the cavity.
Your sealed fireplace should have an air vent in it, seal it up any way you like.
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[Perry525]

From the photos, it looks as if the house is in a hole and the ground is raised all round?
The space between the raised garden is covered in concrete?
How does the rain water get away?

The photos show that the dpc is well above the concrete surround? Is that correct?

Yet the front wall is damp = cavity wall?
Have you checked the fit of the plastic windows?

More often than not, plastic windows are fitted carelessly and in a hurry. The fitters take little time to fit them correctly and there is often space for the rain to enter.

Do check the fit by knocking off the internal plaster to see if you can see the outside world through the gaps round the windows. (You probably will)

While doing that you can check how the walls round the reveal were insulated and finished and look inside to see if there is any insulation and if there is, if it is wet.
Or the outside wall is wet from the rain running through the gaps.

Then you can use a low expansion foam to seal them properly.

If after that, all is well, so far, then.

If you feel the poor work on the electrics is the culprit then remove the mortar and test.

The air vent below the floor is there to allow a cross flow of air to help keep the joists dry. Are there matching vents in all outside walls? Are all the ground floors made of wood? You need vents on all sides for the passing wind to suck the air through.

The key thing here is, that ground floor joists and floor boards rely on the heat conducted and radiated from the rooms above to keep them at a higher temperature than their surroundings and thereby dry. If there is no heat then, the wood will reach the same low temperatures as the surroundings and you will have condensation on the timber leading to rot.

If I understand, you write that an air vent was added to the front room later?
I cannot imagine what that was for?
Block it up! There is no point in letting cold air into a room and allowing expensive warm air to escape.

[Perry525]

Sorry.stopped for dinner.
From 2016 all new builds will have to be of Passive House standard.
This means in effect that all the past concentration on ventilation will go out the window.
To save fuel and power all homes will be made as airtight as factory building can make them
And ventilation will be mechanical and controlled.
Stoneyboy is correct that chimneys can become damp if not ventilated.
But, lets look at the problem.
A chimney is but a single leaf wall that has the insulation factor of a double glazed window.
As such it is cold!
During winter you see what happens to your windows on cold nights - in the morning they can be covered with condensation and in bad cases this can run onto the window cills and into the walls.
A chimney is the same, except that the damp sinks into the wall makes its way through the wall into the chimney and up and out into the cold outside.
So, you have two things.
A cold wall that attracts most of the water vapour in the room and becomes damp.
And a total drain on the heating as a lot of the heat makes its way out of the room and up the chimney.
Perhaps, you may consider how better to stop this movement of heat up the chimney?
Get rid of the chimney?
Insulate the chimney?

[pyramid]

Hi Perry and Stoneybot thanks for the info. Just as I got stuck into this the work came flooding back in so not much progress yet. I pulled the socket out of the wall tho and a tv aerial located close by...... it was soaking and the sparkies left the bricks they bashed out in the cavity wall. so there we have it... prior to my arrival the cavity had been bridged by first the sparkies, the the tv aerial company then a damp problem arose and the guys brought in to solve it stuck a poorly fitted air vent in the wall which caused the problem to grow even worse!
Anyway that said my next move is to run the TV aerial and 2 sky plus leads from the outside through the holes of the original underfloor vent which is just below the DPC to under the floorboards then behind the skirting. Does this sound ok?

[stoneyboy]

pyramid,
Make sure you form a downwards loop in the cables so rainwater is not directed into the house.
end

[pyramid]

thanks Stoney, the thought hadnt crossed my mind. Does anybody know a good product to fill the holes which were created in the brickwork? for the cables to come through

[pyramid]

Ok so if you have looked at the pics you can see where I have knoked off the plaster 1.5 metres high. I have now decided to knock the rest of the plaster work off, not by choice though but above the window is really bad so it will have to come down. I will then attach metal studding to the brickwork and screw on some plasterboard sheets along the main wall (the one with the window in it). There will be a small area on the wall next to the door of the same height but only about 200 mil wide. I am thinking of 'sticking' the plasterboard straight onto the brickwork as if I use the metal studding here then the wall will protrude too far past the door frame. I am debating how to attach the studding to the brickwork, the options I am aware of are:-
1. To hammer nails through the studding into the brickwork (is this feasible? I am worried about blowing the bricks? am I thinking too much? hmmm I wonder.
2. To drill through and push some wall plugs in to screw into?
Anyone who has followed this post might be wondering what the hell ive been doing, well, sorry for the lack of pace so far but have had work away from home and, well, the bank account is in dire need of some replenishing. I am off for a week now so hopefully I will make alot of progress and the questions raised and answered here by the end of this mini adventure I sincerely hope will help another unfortunate soul.
p.s I have decided not to plaster due to costs and time, I will need another person but with the plasterboarding I can jump straight in.

[pyramid]

New problems have now arised......... hopefully I can miss work again next week, I have been staying fairly optimistic about the challenges ahead of me. It has now become aparent that the floor joists need replacing in the entire hallway (I haven't even checked the stairs yet and don't know if I want to!) and also part of the joists in the front room. There is also a piece of 4 by 2 which runs along the brickwork which the floor joists sit on top, that is so rotten I can push my finger right the way through it. with no money in the bank account and a bunch of lazy ass friends it is down to me and my non-existent experience to rectify, quickly, I have tenants lined up and desperate to move in! My plan is to jack the joists up using a car jack with a piece of strong timber attached to the top. I reckon I could lift 3 joists at a time this way. I would then have to cut the 4 b 2 between the 3rd and 4th joist and replace that short piece. Then I will moved along and lift the 4th, 5th and 6th joist and repeat the process all the way along. Once that has been completed I then need to find the good bit of each joist and somehow attach new timber of the same size, (any ideas on how to attach this?) which will run down to rest on top off the new 4b2. I will then cut away the bad piece of the old joist. The door frame from the front room is also rotten, shoild I replace this or can I get away with leaving it? Any help would be greatly appreciated, am in over my head but just have to get on with it.

[pyramid]

one more thing, there is loads and i meen loads of rubble mixed in with the insulation in the cavity wall. I have started at one end and removed the lowest brick possible (one brick above the dpc) to get my hand in to clear it out. I can only think of doing this all the way along the wall in order to clear it properly but with all the other problems I dont have time as I spent one day clearing 2 bags of rubble and haven even moved along the wall yet. Does anybody know of a quicker way to do this?

[stoneyboy]

pyramid,
"My plan is to jack the joists up using a car jack with a piece of strong timber attached to the top" - Suggest you do this and use a brace to hold up the joists and then do the next along, you will then be able to fit a longer piece of wallplate.
"I have started at one end and removed the lowest brick possible (one brick above the dpc) to get my hand in to clear it out." This is the only way unless you are prepared to rebuild the outer wall completely.
end

[pyramid]

I have made progress with the joists. Because there is no such size as 4 inches by 2 inches (apparently), even though the wood is sold as 4b2! I have painted the brickwork for the wood to lay on with a bitumen, then I have laid a new DPC and then I have had to lay down two layers of slate to make up the height difference. I have attached the new joists to the old joists (I have cut the old joists back) with 10mm threaded bar and a square plate either side -

http://s699.photobucket.com/albums/vv35 ... g&newest=1 -
- http://s699.photobucket.com/albums/vv35 ... g&newest=1 -

The joists were still laying a few mm to high so I have packed them up further using some plastic window packers. Today I am going to 'tie' the joists into the wood laying on the brickwork using some angled 'cleats?'

The hallway area is baffling me, I have raised the floor boards and cut back the joists. The underfloor air vent had been blocked up in the past so I have cleared that out to allow an airflow. this area was by far the wettest so have left it over the weekend to allow the bricks and everything else to dry out. Unfortunately, even though we have had a few hot days, the bricks still feel very damp and I cant seem to locate the source. the area in question is the corner of the house, on the outer side is a drain where the drain pipe leads to, there is a small hole in the concrete of the drain which leads through to the bricks which I will fix but am not confident that this is the main source due to the excessiveness of the damp. My biggest worry is there is a leak from the drain further down.
How would I test this? and how could I fix this? ANY words of advice would be greatly appreciated.

[stoneyboy]

pyramid,
Wet bricks will take a long time to dry out, months if they are not in a ventilated position. From you description of the downpipe I suggest you run a hose into it and see if the water runs away - the drain may be blocked.
end