Damp spots in bedroom

[Makingthemostofit]

Hi, hope to get some good advice re damp proofing a bedroom. Our 70s bungalow is situated near the sea so lot of moisture around naturally. House no longer lived in only used occasionally for family hols. One bedroom has a workshop attached to one outside wall and it seems that is causing some dampness in the room, and there is a terribly moldy damp spot in the furthest corner to ceiling. Is dry walling a good idea, perhaps just the two outside walls affected most? Any other suggestions, don't have much experience?

We had this is DS's bedroom corner (Victorian terrace but this is on outside wall). Blitzed the mould with Mould Killer, washed it down and painted it. We put a Unibond humidity absorber in there, with tablets, and keep the windows open for half an hour a day. It seems OK now - i.e. no mould for about four months.

if the house is generally empty, and is kept properly ventilated, it is less likely than usual to be condensation. Is it ventilated?

Look more for leaks, including roof, gutters, plumbing, loft tanks; and problems where an extension or outbuilding abuts the house, and water may be splashing up or not draining away.

Sniff under the floors. It is damp? It should be cold, dry and draughty, like the loft.

Look for ground levels outside or paths bridging the DPC or blocking airbricks.

Turn the water off and see if (1) it reduces dampness or (2) loft tank water levels drop

Now that the frost has gone, leave the loft hatch open, and this will encourage airflow up and out

I don't understand where the damp patch is. What do you mean by "in the furthest corner to ceiling."

Thanks cloud and piglet, will try the mould remover and repaint definitely. There is no water coming down from attic, already been checked. But maybe splashing or water not running off too well from outside could be problem.
Re corner I mean the corner of the adjacent outer walls where they meet ceiling, where shed is located behind one of these walls. Seems condensation hit the coldest part of room. Windows on ventilation setting to allow air movement throughout house, so mould has not increased. It's just a recurring problem and I'd love to be able to fix it on a more permanent basis. Cheers

Personally I think you're wasting your time redecirating before you've found the source of water, cured it, and the wall has dried out.

An empty house, well ventilated, with no steamy showers or wet washing draped on radiators, should not have damp patches.

Have a look at the gutters and downpipes near the wet wall.