Damp in first floor bedroom, 1900 brick built house

[Teresa]

In a north facing bedroom, 1900 yellow/London/Cambridge solid brick house, there is damp in the front wall.

Below the single glazed sash window, the wall plaster was showing 8 out of 10 on my damp meter. The plaster was falling off, so I managed to pull some off - kicked it hard and it fell on the floor, actually. Took the reading again and the bricks show 0-2 further away from the window, but two bricks closest to the window on each side showed high readings 6-8, the lime mortar between the bricks show higher readings than the bricks it surrounds, all over the section of the wall. After one week of the plaster being off, I took further readings and the damp readings appear to be a bit lower on those bricks are 4-5 instead of 6-7.

The plaster under the window was ropey when we moved in in 1999. There was secondary double-glazing for sound in the room until about 6 years ago, the previous owners drilled through the window frame to insert a cable of some sort - I left it open for ventialtion and to dry it out.

The room does have a condensation problem, I pulled out a built-in cupboard in the far northern corner riddled with mould about 8 years ago. Behind a wardrobe, we continued to get mould in the far north corner.

The flat bay window roof outside this window was replaced about 5 years ago - the flashing had been breached in a flash rainstorm in 2005 and, though sound, it was not well connected to the brickwork. We had the baywindow roof insulated and re surfaced.

There is a stone string across the front of the house immmediately below the stone window-sill. The plaster in the other small front room is damp, but not as worryingly high as in this bedroom. I believed for years that this was the culprit.

There is historical subsidence in the far north corner of the house, but it had been checked in 1996 and again in 2008 and the surveyors have said it has stopped moving.

The chimney breast had no proper ventilation grille in it, so we opened out the chimney. There is a wood-burning stove in the room below for the last 3 years, the chimney is lined.

For most of the year, the window is left open, but in winter, we keep a dehumidifier going in there. Last summer, the damp reading was still 5-8 in an arc from under this window.

We plan to insulate this wall and install double-glazed window, but am unwilling to have this done until I know exactly how it should be done. As you can see, we have been doing the simple tasks to see if they sort things out.

Over the years, I have had numerous damp-proofers, limeplaster bricklayers, plasterers, builders and interested parties look at the wall and give advice. Three bricklayers have said the outside does not need repointing. Two builders and a surveyor have suggested the stone string is not causing water penetration.

We have been in the house 13 years and have had work done on other parts, but this is a problem which is proving intractable.

So, my heart leapt at the prospect of the wall drying out once the internal lime plaster was off, but I have been disappointed so often in the past.

I have tried to give as complete a picture as possible because I have been unable to attach a picture.

[RoofingDave]

For the Flat Roof you can use Firestone EPDM.

You can get it from Roofing Warehouse for £6.95m2

Firestone EPDM