Has anyone rectified slab heave successfully

Mauromario · Oct 04, 2020 12:03 pm

Well done to walk away in some way its true waffle is not cheap, compared to drainage which should be included in every build if its so important, why should the owner were the cost of having waffle, when its the builders responsability to install drainage around your home in the first place.

And the gentleman is right the cost in maintaining waffle works out to cost more than the old style raft slab, due to dont put garden next to your footing avoide watering next to your footing you must install paving around your home it must be sloped away from your home, all these extra things that the owner has to do just to protect the footing because once water gets under the waffle it becomes a floating boat, why should the owner have to go go through all these expenses expenses to give the builder more money and your house is not built to last the 40 to 50 years its crazy, we also have a 60 year old home and its starting to show its age now, not like the new home we built 6 months in after hand over he had problems allready, how is this any cheaper for the owner. If tnere is ever a next time i am going stright onto a raft slab, like i had in the 80s i had a pergola up against the house with ferns and other plats and i had installed overhead sprinkler to keep my fern moist, over 15 years not even a hair line crack nothing so we had no maintenance to worry about no sloping land away from the house no extra drainage to be installed no extra nothing, so how does waffle compare to old raft id rather have the old raft over waffle any time long tirm its cheaper don't have to worry about heave or any other movement due to waffle slabs they absolutely crap. Never never again.

Joker · Oct 05, 2020 12:18 pm

The worst problem with waffle slab is that just about every thing has to go well to succeed in its core job,and has we see all the time,one wrong or poor step can and often does cause massive issues that take years to never fix properly,buyer beware.

alexp79 · Oct 05, 2020 12:42 pm

Waffle pods are faster to install, as proper rafted slab generally requires extra formwork (including permanent one for trenches), back fill (sand, gravel) with layered compaction (never backfill with clay!), excess soil removal - all altogether adds at least 1 week to the timelines and $10-15K to labour and material costs. On the other side, depending the weight of your house and soil conditions, there are opportunities with rafted slab to save on piers.

But I think the main problem is that builders/engineers never word out the actual risks and alternative options to the customers to allow them to make an informed decision by themselves.

Everyone (well, almost everyone) just goes with waffle pods without even considering other options. For a customer, $15K extra for $500K+ house won't break the bank, especially in the areas where soil conditions are not ideal and they are already paying extra for site works. $15K extra to sleep well and make sure my house stays intact no matter what, is not a huge added cost. I would rather put in some cheaper (but still good looking) tiles, put in good quality laminate floors vs hardwood or and get an IKEA kitchen (which still comes with 10 year warranty) - all those can be easily replaced later, however, it will be impossible to replace a foundation.

Just my 2 cents.

Thi · Oct 05, 2020 2:10 pm

Agree. Not many are informed. It is natural that people would opt for cheaper slab.There is no incentive for volume builders to do raft. More time taken means lesser return for them. Volume builders now all say no to raft slab, you can't even ask for option. Not only raft slab cost more money, more time, it also has more processes. Which means more admin work to source for contractor. Which is not efficient for big builder. Their job is contracting your build, not building your house. Waffle means lesser work and more profit margin for them.

alexp79 · Oct 05, 2020 3:09 pm

There are also other decent alternatives to waffle pods and rafted slabs such as Cupolex system which is even more cost/time effective than waffle pod much more reliable when it gets to preventing slab heave when comparing to waffle pods.

MBX3 · Nov 16, 2021 8:32 am

Apologies if I am hijacking the thread but I believe all involved may be of some help to me

Our slab has now bee poured but I have found a discrepancy in the structural comps and structural plans used for the construction.

This is set of slab comps where design engineer has used 1N16 as bottom bars for calculating slab strengths. Yes comps show that the capacities surpasses the design forces, however these numbers are based on the wrong sized bars. Assumes that builder has used N16 for rib reinforcement.
Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅

Below is the footing spec shown on the endorsed structural plans that builder used for ordering material and boxing up slab.
Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅

Questions:

Am I within my rights to query the structural engineer that why they have used N16 for computations but then specified a smaller size N12 reinforcement bars in actual structural plans?
If this indeed was a stuff up from engineer, what are my options noting that the slab was just poured last week.
Can a Bobcat driving over the new slab that has only had 72hrs (3 days) of curing time a problem worth bringing to Engineer's attention? (mostly kept moist/wet by the horrible weather we had this month in Melbourne)
We also saw builder not managing drainage for the site. We have large volume of stormwater ponding within 1m of new slab. Structural plans call for clay fill grading site away from footings but builders have just sprayed some Class4 recycled concrete/bricks to deal allow mud-free area for bricklayer. Site Supervisor said they would fill all edges of slabs 75mm below edge beam. He says that should help me pave sideyard & backyard without having to cut/excavate. Does this sound acceptable even if there surrounding ground was grading towards the footings?

Background - Class P waffle pod slab on underlying silty clay, controlled filled clay site with level 1 certificate by developer but independent soil testing revealed some areas have <50kpa bearing capacity , Engineers adopted perimeter bored piers costing me $$$$ that I shouldn't have been paying for (planning to take developer to VCAT as they refused to pay for my bored piers) . No piers in the middle under internal load bearing walls for a single storey skillion roof trusses.

Any advice would be appreciated.