Replacing W shaped timber loft roof supports....?

[The Riviera Kid]

Hi folks, long time no post. I'm hoping somebody can offer some advice here. We could do with making better use of the loft space on our approx 20 year old house. Currently the supports for the roof are a W type arrangement, which offers a reasonable space down the middle of the loft but no easy access to the sides.

The floor has been partially boarded to allow it to carry some of the usual junk (mostly lightweight), and I appreciate the joists may need upgrading if any great load is to be carried.

There seems to be enough headroom for a loft conversion in the future, but I'd like to tackle this in stages. What I'd like to do initially is remove the W frames and replace them with either a single beam supporting the whole roof, or maybe even a beam and a single vertical support in the centre.

I appreciate I'll likely need to get the experts in for a definitive safe answer on this, but I'd appreciate some feedback/views. I can take a few snapshots if needed. Is it likely to be an expensive job to replace the structure with a beam, and if so has anyone got a rough ball park idea of price (the house is a 20 year old end terrace and the "footprint" of the loft is approximately 8m x 5m)? Again I wouldn't expect anyone can give a price with any great accuracy, I just haven't a clue if it should cost £50, £500 or £5000.

 

[Chukka63]

ball park figure with no plans,15-20k.loads of different factors can alter the cost many times over.
a SE is needed first to determine how the new joists will be supprted and there size.the joists will also be supprting the roof.
have an already boarded loft actually adds to the cost of any conversion if you expect the builder to remove them.
you may need PP and deff Building regs.
if velux windows are to be used,bare in mind they will be noisy when raining