Hi all, hope someone can give an opinion or advice on this... in any case it might be a good laugh for you. ;-)
(NB "I" refers to me and/or various contractors.)
I'm renovating a 1930s semi - where virtually every "improvement" that's been done to it in the past has been a bodge: driveway covering is breaching DPCs, badly installed DG (cracked units with condensation inside), lack of lintels over side wall windows, "patio doors" with no support causing the back bay to sag a bit, etc. It's a basically good house in a great area that I got at a good price in December 03, and the problems are all pretty obvious, weren't a surprise (had lots of various surveys) and the job, while huge, is under control and budgeted - but one of the items is causing me immense problems.
As you can infer from the age and style, the original porch was a brick archway with the front door divider set back a couple of feet. The front door divider had been removed and the hallway had been extended forwards into the porch area by fitting a plastic door frame into the archway itself, concrete filling in the porch floor area to raise it to the height of the hallway's timber floor, extending skirting boards either side of the hallway to abut the front elevation, laying underlay+carpet to the door, boarding and artexing the ceiling, painting the inside brick on the front elevation, and externally using bricks and flags to form a step up to the door. Looks fine, and you can take yer coat off without banging yer elbows on the stair banister.
First: musty smell in the hall, caused by penetrating damp and insufficient ventilation. Mould was plainly visible on the front elevation (bubbling paint, black spots) and under the wallpaper where originally it would have been external wall.
I got rid of all the paint and wallpaper, ripped off the skirting boards (they had been extended by adding small pieces, I'm gonna put a single piece on each wall), removed the plaster on the side walls well back from the infected area, ground out the infected mortar on the front and side elevations, burned and treated the internal surfaces, re-rendered the internal side and front elevations with waterproofer and sand+cement (imagine the fun I had fitting the beading to form the archway...) and Thompsoned the exterior side and front elevations.
To get some ventilation in the hallway itself my plan is to put two air bricks, one at calf height, one around ceiling height, in the side wall, to get a "pull" with negligible heat loss. Hallway is the coolest part of the house anyway.
OK, so musty smell was dealt with, even without the extra ventilation. Grrr - hairline cracks in the render though, there's some movement in the walls (big trucks going past, even on this quiet road) - have to get some basecoat before I cover it.
Not long afterwards I started noticing a ghastly smell coming from the underfloor area in the hallway - the skirting boards are off, remember. Turned out there was a blockage in the airbrick servicing the front part of the hallway, so cleaning it from the inside rather than just the outside solved it in a few days. Removing some of the deleterious material under the floor will also help, I'll get round to that at some point. I'm also gonna replace that airbrick with one with a higher flow, and add a second one to the side elevation as well. Can't hurt.
Next task, and this is where it starts to get interesting (as in "may you live in interesting times"), was to get rid of the concrete in the filled-in porch area and put in a TSF to match the rest of the hallway - this'll enable me to put an airbrick on the front elevation under the door sill too, to get front-to-back underfloor airflow. The concrete was attracting condensation too, it had to go.
I turned back the carpet a few feet, and smashed and drilled out the concrete, which was a bit sandy and soft, as it turned out. So I'm left with a hole-in-the-floor and a gap in the front elevation underneath the current door sill, cos the concrete had been used instead of a brick course - presumably this was an off-the-shelf door frame and didn't fit exactly.
There were obvious salt deposits on the side wall bricks to the lower part of the porch area, caused by rising damp I would assume. They aren't any higher than the second brick course above the original porch, i.e. floor height, and the contamination doesn't go back more than 2 feet on either side.
I thought I'd leave it for a bit, cos I had to concentrate on other things, but now I'm noticing that the atmosphere in the hall (and by extension, because of the extreme ventilation from the gap under the door sill, much of the lower part of the house), doesn't actually SMELL bad but, much more insidiously, TASTES of salt, making eyes sting and sinuses tingle after just a few minutes. Most people don't notice it because it actually feels nice and fresh, a bit like a trip to the seaside...! And when the contractors are here the front door is open all the time for coming-and-going so it doesn't become noticeable.
I've managed to confine the problem to the ground floor rooms by keeping all doors closed, especially upstairs so it's not drawn upwards.
Is this unusual? I mean, salt contamination is a pretty well-known issue, but should it be this uncomfortable? Perhaps the problem is exacerbated by the big hole under the door sill and lack of heating (the hall radiator is off, of course... so I can get the skirting boards back on...)
My plan to address this is as follows.
I'm already digging a temporary "french drain" / "soakaway" all around the house, cutting back the bad driveway, which I intend to replace in the next 5 years anyway - this should reduce the lateral pressure. (The front and back steps will form "bridges" over the soakaway.)
First, clean the internal surface of the brick work - what do I use for this? Is there a specific salt neutraliser? Shall I do it several times, a few weeks apart? Shall I try to seal the internal surface in some manner or will it travel if I do that?
Second, apply a chemical DPC to the affected few feet of side wall on both sides (internal wall and outside wall, that is), and link it to a new membrane in the brick course under the front door sill on the inside of a newly-created cavity wall underneath that sill.
Third, install TSF, and make sure no wall render or plaster touches the floorboards.
Fourth, install skirting boards on all elevations, and use a lot of paste/glue/sealant on the wall and floorboards to create as much of an airtight environment as possible and hold down any rising "bad air" which can be removed by the extra underfloor ventilation.
Whaddayathink...?