mdf: Are you coastal (salt) or near airports, flightpaths or busy roads (petrol fumes)?

Nope, nope and Nope.

I'd go with Selleys sugar soap, use a soft broom to apply and rinse off with hose. Perfect for paint prep

mdf: Resene sell a house wash and paint prep. Sugar soap will work well too. Officially you're not supposed to use a water blaster as you might gouge the weatherboards. I always use mine and have never had a problem but obviously discretion advised. Don't use a petrol one for this though!

Water blasters are usually never a good idea with cladding. Mainly because the water can get forced under flashings and behind the cladding. Also many houses of that era may not have head flashing on their windows, as they rely on teh overhands from the soffits for weather protection. So the water just goes straight into the wall cavity and damages interior wall linings and trims. Thus you end up with a far bigger job to resolve.

mattwnz:

 

mdf: Resene sell a house wash and paint prep. Sugar soap will work well too. Officially you're not supposed to use a water blaster as you might gouge the weatherboards. I always use mine and have never had a problem but obviously discretion advised. Don't use a petrol one for this though!

 

 

 

Water blasters are usually never a good idea with cladding. Mainly because the water can get forced under flashings and behind the cladding. Also many houses of that era may not have head flashing on their windows, as they rely on teh overhands from the soffits for weather protection. So the water just goes straight into the wall cavity and damages interior wall linings and trims. Thus you end up with a far bigger job to resolve.

 

can you use air blasting?

joker97:

 

mattwnz:

 

mdf: Resene sell a house wash and paint prep. Sugar soap will work well too. Officially you're not supposed to use a water blaster as you might gouge the weatherboards. I always use mine and have never had a problem but obviously discretion advised. Don't use a petrol one for this though!

 

 

 

Water blasters are usually never a good idea with cladding. Mainly because the water can get forced under flashings and behind the cladding. Also many houses of that era may not have head flashing on their windows, as they rely on teh overhands from the soffits for weather protection. So the water just goes straight into the wall cavity and damages interior wall linings and trims. Thus you end up with a far bigger job to resolve.

 

 

can you use air blasting?

 

Is there such a thing, apart from an air compressor? There is sand blasting, but that would rip apart the boards. That is usually used on concrete to clean it up nicely. Washing with a brush and sanding or heat stripping is probably the best approach, but is time consuming work. But from my experience, you have to do this sort of work yourslef if you want it to be done well, because tradespeople will often be trying to get it done as quickly as possible, which often results in shortcuts.

mattwnz:

 

mdf: Resene sell a house wash and paint prep. Sugar soap will work well too. Officially you're not supposed to use a water blaster as you might gouge the weatherboards. I always use mine and have never had a problem but obviously discretion advised. Don't use a petrol one for this though!

 

Water blasters are usually never a good idea with cladding. Mainly because the water can get forced under flashings and behind the cladding. Also many houses of that era may not have head flashing on their windows, as they rely on teh overhands from the soffits for weather protection. So the water just goes straight into the wall cavity and damages interior wall linings and trims. Thus you end up with a far bigger job to resolve.

 

I hadn't thought of that - it's a good point though. That said, if water is getting in from water blaster spray, it is probably getting in from hose spray too? I mainly use the water blaster since it uses less water, and the fan shape is great for running along each weatherboard (rather than a hose where it kind of goes everywhere, including blasting dirt onto the areas you've just cleaned).

mdf:

 

That said, if water is getting in from water blaster spray, it is probably getting in from hose spray too?

 

Absolutely, infact many house older than 2000ish may not have head flashings under the verandah of soffit overhangs, so you should never really spray any water up above the top of the window, otherwise water can just  flows straight in the top. These days that sort of thing isn't permitted with new buildings, and you would hope council building inspectors would pick it up.

Sugar soap.

Vigorous scrub with a stiff bristled brush - this will also take flaky paint off.

Rinse off with throughly - high volume, low pressure.

Look forward to sanding, sanding and more sanding.

Oh and filling and (wait for it) more sanding.

Happy times.

Okay sugar soap seams to be the favorite. 

Follow up question, what is the best tool/method of getting into the swooping contour of the 'Wellington Profile' style weather board for sanding and scraping? 

Normally I would just use a heat gun, but for whatever reason my heat gun just can't remove this paint.