Serving the greater Auckland Area since 1988
The same generic description is used to cover three quite different systems, all applied over light wooden framing. The brief discussion below is generally about claddings applied to existing houses:
This is the oldest, essentially a reinforced sand/cement mix which is applied over a rigid sheathing such as thin fibrecement (commonly "Hardibacker") or just applied over building paper. There are still plenty of "Art Deco" type houses around the country dating from seventy years ago clad like this. This style experienced a resurgence starting in the 1990's. The plaster mix is usually around an inch or 22 - 25 mm thick. There should be continuous concrete footings around the edge supporting the outside walls, to minimise movement.
EIFS is an acronym which stands for "Exterior Insulated Finishing System" and means plastered polystyrene. This started during the rebuilding in Germany after the second world war, moved to the states and finally arrived here in the eighties. The early versions were fairly basic, by the late nineties the three main companies (the market is quite competitive) were all developing good weathertightness details. The plaster is a sophisticated factory batched mix with various additives, reinforced but generally only about 3 mm thick.
These are usually 2.4 x 1.2 sheets 7.5 mm thick with rebated edges which are filled with a reinforced plaster mix to create a uniform finish. Sometimes just the finish paint is added, in other cases the entire surface is plastered. Some photos of a typical problem with this cladding here. "Harditex" is actually a proprietary product produced by James Hardie. When this became popular during the 1990s, a number of competing products appeared on the market, it is not always easy to figure out whose product you have on your house.
Stucco is frequently criticised because the mix is made on site where there
is no independent check on the quality. Many variables can effect the quality
of the mix, there has been quite a lot of publicity in Auckland especially
about high chlorine contents causing premature corrosion of the reinforcing.
Whereas the other two use factory mixes which are less susceptible to such
problems. Solid plasterers were more often specialists in their craft and
they may not have checked all the required flashings were in place - they
probably considered this was the builder's job. Whereas the EIFS claddings
have been full systems for many years - the licensed applicators usually
applied all the flashings as well. It is hard to say which is the worst
of the three "monolithic" systems. but building surveyors will
generally admit (in private) they have never seen an untreated wooden framed
house with direct fixed fibre-cement cladding that 'works'. There are several
reasons for this, very briefly it would be fair to say it is extremely difficult
to fit these sheets exactly in accordance with the manufacturer's instructions
- even small variations or omissions can have disastrous consequences.
Which makes later versions of EIFS (generally) the lessor of the three evils.
Water gets past the outer surface and cannot escape fast enough, so the framing starts rotting. It really is that simple.
Nowadays the mantra "All houses leak" is widely repeated and believed - but not so between 1994 and 2002. In that era it was equally widely believed that houses could be built so they didn't leak - or at least, any leaks would be so small and short lived no problems would develop. This has turned out to be untrue. The problem is generally with all the gaps and holes in the outer skin - wherever there is a window or a door, for instance. Water sneaks in at the junction between the cladding and the window or door and it cannot escape or dry out quickly so it soaks into the framing. Not just here - water may soak up from the ground outside, or run in from the edge of the roof....the list of possible entry points is virtually endless.
A good way to understand the changes the residential construction industry has gone through since about 2001 is via the 4 Ds. This also helps to understand what is wrong with so many of the houses built during that 1994 - 2002 period:
If the roof sticks out, it will protect the walls and reduce the amount of water hitting them. No eaves puts a greater demand on the cladding.
Drainage (the cavity concept)
If the cladding - whatever it is - is stood out, away from the framing then any water getting past has an easy route to run away - like brick clad buildings have always had.
Good air circulation means any wet building material can dry out again quickly. This is achieved by ensuring there are small gaps along the bottom of the cavity - generally this is all that is needed. Additional gaps along the top are sometimes seen (especially with brick).
If all the materials - especially the framing timber - is durable enough, it doesn't matter if a little bit of water does reach it every now and again, this wont be enough to allow rot to start.
So when you look at a typical monolithic clad house from that period 1994 - 2002, it is easy now to see how frequently none of these four concepts got a look in - no wide protecting roofs, so more strain on the wall claddings. No drainage because the cladding was directly fixed to the framing. Likewise, very limited air circulation in there to dry things out. Finally, kiln dried untreated timber which can rot frighteningly fast.
If you have a house like this, you have three basic options. Doing nothing is certainly one. Depending on your circumstances this might be the best one. Older people who decide they have better things to do than worry about this are one such group. Why bother - let the kids deal with after you have gone. The other two main options are: fix it now or do temporary repairs to prevent it getting worse until such time as it can be more "permanently" fixed. Before facing either of these, you need to know more. Read about Surveys and Reports.