Window Sill Replacement

[Funkadelic]

My window sill has slowly rotted over time due to the window not fully closing and water dripping down when its raining. I have now fixed the window and looking at the best way to repair or more than likely due to the size of the area that has rot taking the whole thing out and replacing.

Is there an easy method to taking the window sill out as a complete piece as Im not certain how it is fixed to the brickwork, I also noticed on one side it is slightly inset in to the wall.

Any tips & help is appreciated, thanks in advance!

 

[foxhole]

May be glued or mechanically fixed or both.Ideally cut into 3 with multi tool and lever out centre piece which should indicate how they are fixed and minimise damage .

 

[Deleted member 174758]

What you are referring to is actually what we call the window board and is on the inside of the window. These often have a rebated edge which is let into a groove across the back of the window and may be secured by being screwed or nailed to the bottom of the window reveal. Relatively easy to replace, although cutting and shaping the horns takes a bit more practice and ideally a jig saw (hand saw will do) and a block plane (to round-over the edges). Be prepared to repair the plasterwork adjacent to the window board as this often gets damaged when pulling out the old window board. You can buy ready nosed sections of window board (MR-MDF and softwood) from most timber yards. They may even be able to rip down and rebate the front edge for you for a nominal fee

 

[opps]

Why not just fill the hole with 2K filler?

 

[foxhole]

Why not just fill the hole with 2K filler?

Fill rotten mdf ?

 

[opps]

Fill rotten mdf ?

It only seems to be a problem in one small area and I assume it is no longer wet.

Chisel/multitool out the worst bits and then use an epoxy wood hardener which will strengthen the fluffy MDF edges.

 

[foxhole]

It only seems to be a problem in one small area and I assume it is no longer wet.

Chisel/multitool out the worst bits and then use an epoxy wood hardener which will strengthen the fluffy MDF edges.

Looks extensive , has lifted paint over a large area. Takes months to dry .Once wet looses its integrity even when dry .

 

[opps]

Looks extensive , has lifted paint over a large area. Takes months to dry .Once wet looses its integrity even when dry .

I can't see much evidence of the paint having lifted over a large area. In image number one, where the board meets the wall, the damage to the paint looks like someone has removed a badly applied bead of caulk.

Whilst not wanting to offend the OP, the irregularities in rest of the surface looks like evidence of DIY quality decorating. A decent random orbital sander should be able to flatten the paint.

You are correct that prolonged water ingress will weaken MDF but it is a window sill and its structural integrity isn't critical.

There are a number of products that will deal with the "punky" MDF (ie the loose swollen fibres). Epoxy hardener works well, as does Owatrol oil.

Over the years I have had to deal with loads of sections of water damaged MDF. I would have recommended epoxy resin filler rather than 2K filler were it not for the significantly higher costs.

That said, it may be easier to replace the MDF if the OP doesn't have access to decent sanders. Personally I wouldn't want to sand it by hand. It is doable but a PITA.