had a conservatory built. the walls are double brick, except were the plastic patio doors sit , this is single brick. Outside we have pea gravel between the brick work and the patio. The problem is on this single row of bricks it is damp. Could it be the pea gravel holding rain water and saturating the bricks. What can i do, does the water repelant coating you can buy help,or should i remove the pea gravel.
This is a classic problem where there is no damp course fitted on the bricks under the cill. However if you have pea shingle covering the bricks on the outside this may be making the damp worse. Try removing the pea shingle so the the whole depth of one brick is exposed.
Your damp proof course is level with the bottom of the door frame.
The bricks below are in contact with the ground and may be dry/damp/wet.
This is normal.
The pea shingle will not transfer water to the bricks and should be left in place.
The damp proof course should be more than six inches above the ground/top of pea shingle, this is to stop rain bouncing up the wall and making it wet. If the top of the pea shingle is high, lower it.
The silicon paint that you refer to, is designed to shed rain water, to stop the rain soaking into the wall above the damp proof course. In this situation, where the bricks are damp/wet because of contact with the ground it will not help.
unfortunately there is nothing that you can do about the colour of bricks that are in contact with the ground. When they are wet they look dark, in the summer when its dry(?) it ever, they will lighten again. The fur, is down to various chemical salts that were in the clay when the bricks were made, the process of getting wet, then drying out, moves the salts to the surface of the bricks. Wet, always moves to cold, once the world warms up, it will go away.