Cost of loft conversion if already partly done

[Christmascookiesmmmm]

Hi! Loft already has 4 velux windows and a few sockets and is accessed via pull down ladder. Survey came back saying they were not able to inspect it as it’s ‘not considered safe to walk on’ and could only store ‘small household items at the most’. I’m guessing they can’t go up for insurance purposes. It has a good head height as it’s victorian terrace so I’m assuming the floor won’t need lowered. So would it just need floor reinforced and staircase built? (Wang a proper staircase that feels like it carries on from first flight of stairs) has anyone done this type of thing and how much roughly would you think it would cost?

We've just had our loft converted. The building work (including two Velux, one dormer) and a staircase cost £34,000. It also has an en-suite. They built a dormer extension though which made a big difference to the cost. Without dormer and bathroom the quote was £25,000.

From what you say, it is not being done to a proper standard.

That suggests that Building Regulations approval has not been sought or granted, and probably not planning permission either.

If you want to do it properly, start from scratch.

It's lucky they haven't done much, because it costs more to strip out a non-compliant loft conversion and do it again, than it costs to do it properly in the first place.

The surveyor's comments give a hint that it may already be unsafe, for example because structural timbers have already been sawn apart.

DIY or bodged loft conversions can be quite a problem. One of the important functions of a roof, apart from keeping the rain out, is to stop the walls falling down. This is far from unknown.

here's one

www.dailymail.co.uk/news/article-3631346/Gone-30-minutes-Terraced-house-COLLAPSES-just-half-hour-building-work-six-months-bought-doer-upper-700-000.html

and

www.bbc.co.uk/news/uk-england-hereford-worcester-44837710

Eerm @PigletJohn that’s quite unnerving?!?!
I’m happy for us to start again with the loft conversion, but I doubt the house would collapse, there are structural beams still and the house in the article you linked said all its internal walls had been removed? The survey said ‘improvements to the loft are visable’, it said nothing about structural beams having been removed- there are two big beams in the centre.

English roofs are usually constructed in wooden triangles and W-shapes. If you cut any of these out the "triangle" is liable to collapse and the walls fall outwards. You can see it in one of the vids, it's a typical collapse. The tops of the walls are pushed apart.

During a loft conversion, the internal timbers get in the way and some people cut them. Sadly none of them are provided as ornaments, they're all needed to maintain the structure. The plans for a proper conversion include providing alternative support before taking away the old parts. The "floor" of the loft also has to be strengthened because it's only been calculated to hold up the plaster ceiling. Modern roofs are carefully calculated to use the minimum possible amount of timber to carry the weight of the tiles and not much else.

It also happens in a bad fire when the roof has partially burned away. The pattern is that on the slope (not the gable) the tops of the walls go outward. Typically the gable walls and chimneys are still standing afterwards.

Very likely the house you're looking at will not fall down, my point was to show why correct design and practice has to be done, and errors can be catastrophic. Building Control is intended to prevent this happening, and an uncertified loft conversion is a bad buy..

ps

A Victorian terrace was probably built with a slate roof, which is light. After a hundred years or so it will have been re-roofed.

Modern concrete tiles are heavier, and can overburden the thin roof timbers, This will show itself in bowing of the roof, visible from inside or out. All of the roof timbers may be too weak without reinforcement. But this does give you the chance to rebuild and insulate to modern standards.

Original Welsh slates are very expensive, but you can get a synthetic slate that doesn't look too bad, from a distance. Some roofers will be strangely eager to take away your old ones and sell them to someone else.

Ah, here we are.

A pic from further down the Daily Mail page.

You can see the buffoons builders have cut away the "floor joists" and braces of the loft which hold the roof in its triangular shape.

Anyone seeing that would should know that the slopes of the roof are in immediate danger of collapse.

And that's what happened.

Perhaps Boris Johnson was working there.

We had a partly done loft conversion when we moved in. Sounds similar to yours but had a proper staircase, and there hadn't been the any reinforcement of the floor. But to do that the floor (and all electrics installed etc) has to be ripped up surely? That was the case with us.
It cost us 5k just to strip it back to how it would have been if the previous owners had never done anything with the space!