How much work in a wooden floor?

[Dean Heighington]

,

They weren't still on were they? ;)

[Andy Burns]

They don't seem to link to the Lite version once you *get* to the site

[GMM]

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Now that's what I'd call a serious floor job! It makes my project look pretty trivial (and all the better for it!).

Was there a special reason why all your joists ran lengthwise? I was thinking that the shortest joist span would be better, in terms of making a rigid floor although, in reality, it's more a matter of following the original design in my case.

I meant it will take until spring just to write the list. Completing it....now there's another matter!

Cheers

[GMM]

=A0 London SW

Nail on the head Dave - that's the whole purpose of the exercise, daunting as it may all look right just now! In the past, my houses have always had some aspects that may not really need doing: No such ambiguity here though(!) - I don't think anything, apart from a re-wire and new heating, has been done on this place in 40+ years. My plan is to do everything well, rather than 'getting by', so I'm afraid I shall be picking the communal brains of this community on a regular basis over the next few months, years, decades......

[Dave Plowman (News)]

In Victorian semis or terraces, the joists run front to back. If they went side to side (and into a wall cavity, as yours did) more risk of fire spreading.

[tony sayer]

In article , Dave Plowman (News) scribeth thus

Umm .. how many Victorian semi's & terraces had cavities?..

[charles]

It also made it easier to run in water pipes from the road.

not a 'cavity wall' but a 'wall cavity' - to support the joist at the end. Nowadays joist hangers are used.

[Dave Plowman (News)]

Cavity as in where the joist sits. On a 9" wall usually created by missing bricks in the inner skin.

[Dave Plowman (News)]

Interesting - but surely most come in well below the joist levels?

[John Rumm]

You will no doubt be pleased to hear it only took about 5 or six days in total then (2 of us).

Two reasons (well one ultimately) - firstly that was the shortest span since there was a supporting wall across most of the middle. Secondly, that was the way the original joists ran, and these had to slot in between them.

More photos may make it clearer:

I meant it will take until spring just to write the list. Completing

Enjoy ;-)

[John Rumm]

That was a 1956 semi, and in this case we were above all the walls with exception of the party gable (and we generally kept a couple of feet away from that)

[tony sayer]

In article , charles scribeth thus

So that was a fire risk then?...

[charles]

why so? the joist was still made of wood.

[chris]

Dear GMM I have done this sort of work for a living since 1975 and without doubt tell them to get stuffed. You will, with guidance, do a far far better job FWIIW you need to determine the following

Why did it rot in the first place? If it is pre 1886 there was no requirement for a dpc in the wall and built in joist ends will rot Its a pound to a penny it is wet rot not dry otherwise you would fall in and you would have seen it so Determine if there is scope for THROUGH ventilation under the floor Absent that go for a solid or suspended concrete floor with insulation Chances are it is ok for ventilation Next IS THERE ROOM? You need the lowest timber (nomally the wall plates) 150 mm above ground level If so fine - sounds like it is OK for room

Assuming that is hte case

Take out old floor

cut in a 225 x 150 mm sub floor air vent from high up outside down at whatever angle is needed to get under the floor for the thickness of wall - say 60 degrees plus or minus 20. Do this every 1.5 m - 2 m of external run (there is BS for this as I recall its about 4000mm sq per m run off the top of my head )

brick up the cavities

install a chemical dpc internally whilst you have access using Safeguard Dry zone on a DIY basis in the two mortar joints at 150 mm or so above ground level (lower if need be)

look at how to support the wall plates - they should be under the wall with the pockets in

this can be done in a variety of ways

honeycomb sleeper wall, brick piers on concrete footings, deep wall plates (ie beams) vertically supported in joist hangers either side [not really satisfactory but last resort] or dispense with it altogether with use of joist hangers or put a plate in line with the joists supported on S Steel bolts set into where the old joist ends were at 600 cc with the plate isolated with a heavy duty dpc and using large plate washers (remember not to put a bolt where a joist will be) and hang in jiffy hangers (as suggested but another) or on steels set into the side walls

get the levels dead right unless you have the room and are replacing the skirtings stick with the original positions for the edges of the floor or you will have all sorts of problems with doors closing etc If you are starting it all from scratch remember that very few Victorian houses are vertical or square! measure up and compromise to what the room is and judge by eye

Use tanalised joists ideally order them to size and get them treated to size so no cuts or put the treated end on the outside wall and the cut end inside dip treat cut ends in OS fungicide overnight so all end grain is well well treated

Tosh nail in to wall plates with 4" ovals (pre drill with 50% diam bits if you are not familiar with doing this to get the angle right

As suggested buy others if needed put in WOOODEN herring bone but chances are that it is not needed if you put a steel over the cellar

without sizes cant comment as to size of joists

Now comes the important bit

put poly or concrete on the oversite to stop moisture coming up put in insect mesh into airvents (not air bricks) vents are 80% air Bricks are 80% brick! put in insulation min 4" between 4" joist and then at least 1" under that you have to do it as you go along! use stuff with inherent foil vapour check then once done put on floor suggest not T an G but boards which have been equilibrated by leaving on the floor lightly nailed for 6 months of heated room then cramp them

Cannot use floor cramps due to insulation so use folding sliding wedges on a nailed batten

Good luck

Chris

[tony sayer]

In article , charles scribeth thus

Yeabut not that it went thru the wall to the other side did they?..

[charles]

They didn't go through; they stopped on the first brick in.

[Andy Dingley]

Plenty. It was a common measure to avoid penetrating damp. However they're too narrow to fit insulation.

[tony sayer]

In article , charles scribeth thus

So that would make fire spread rather difficult then?...

[tony sayer]

So how did they do that then?, a cavity wall as such but a very thin cavity?..

[GMM]

Thanks Chris, for a comprehensive post.

I think the problems are definitely a combination of damp in walls (it's an 1840 build), leading to wet rot in the joist ends, and lack of decent ventilation. Clearly both of these need to be sorted.

I'm going from memory and surveyor's photos mostly, so can't really plan this in detail until we complete but the current floor (over the cellar) has been supported with a few modifications over the years, including a steel running down the centre of the joists. If this is well fixed, I might see if I can leave it and incorporate into the new floor.

It seems to me that the easiest thing is to start from a timber wall plate, bolted to the wall (probably at 450mm cc, which might be overkill, but can be staggered without having to think!), then joist hangers holding 47 x 225 joists (the span is ~4.3m). Although steels, sleeper walls etc are probably better, it's a lot simpler to work with timber.

I might look at re-using the old floorboards, not to save cost but because they have been well conditioned to the environment. This will depend on their state and whether I have to cut many to lift them. And, of course, whether SWMBO wants a carpet or a bare wood finish.

I'll undoubtedly be back with more questions when I get closer to the job!

Cheers