Some people refer to these as ‘spiderweb’ cracks but the technical name is ‘mapping cracks’.
That’s because they can look like a street map.
Generally they are much more obvious after rain as water seeps doown into the cracks.
These cracks are typically only 2-3mm deep and are as a result of the surface concrete shrinking more, and sometimes faster, than the underlying concrete.
The reasons for this greater/faster shrinkage include:
■ Adding water to the mix, when the delivery truck arrives on site, to improve concrete workability.
■ Starting finishing while ‘bleed water’ (standing water after placed concrete levelled) is on the surface
■ Sprinkling cement powder to soak up ‘bleed water’.
■ Letting the surface dry without Proper Curing .
Although the cracking does spoil the look, it is a cosmetic issue and it doesn’t significantly affect the strength of the concrete.
I do, although I don’t see too much ‘Reality’ in this Reality TV Show.
What’s Unrealistic
The Judges Opinion’s – In ‘Sky High’ and ‘Glasshouse’ we had one winner and one second place from contestants that regularly got marked down by the judges while some of those that were regularly praised struggled to make money. This was in spite of contestants that the judge’s liked getting much more money to spend on their apartments.
Tradies Work Practices – It’s remarkable what Tradies will put up with to get their faces on the TV so don’t expect:
Tradies to drop everything and rush round to start your job.
Different trades to work on your job at the same time.
Any work to be done after 4.00pm.
Suppliers – Don’t expect any special deals on unusual fitting, or same day delivery . . .next week is more likely!
What’s Realistic
Keith – There is always one ‘A#^e h#%e’ on every job who keeps saying “You can’t do that!”and you have just got to learn to deal with them.
The Importance of Programming – The producers seem to delight in having Keith’s team working on the structure at the same time as the contestants want to finish their rooms . . . so the contestants are held up. . . but it does show that you need to make sure the structure is right before you even think about finishing off works.
Stress – There will always be some stress on a building project. Unrealistic timescales and living on the job and it really does multiply.
No Downlights – In the episodes I have seen their seem to be a noticeable lack of down lights. Perhaps this lighting idea really has ‘Jumped the Shark!‘
Have I got it wrong? Are Shaynna, Neale andDarren really the style gurus they think they are?
One simple thing to improve the quality of concrete is to use a spray applied curing membrane. . . it’s a pity that this techniques doesn’t seem to be used much in Australian domestic building.
Purpose of Membrane
These membranes main purpose is to prevent the loss of moisture during the Curing Period.
Some membranes can also help with surface hardening the concrete and help prevent dust.
Types of Membranes
When looking at types of membranes you will find
Water based
PVA based
Chlorinated-rubber based
Resin based.
In my opinion a water or PVA based membrane will be quite suitable for the typical house slab or driveway.
A further consideration is whether to use a clear membrane or a white pigmented material.
Unless I was using the compound on a coloured concrete, or an exposed aggregate finish, I would go for the white pigmented finish. It has the following advantages:
The colour makes is easier to check the whole surface has been covered evenly.
The white colour, which will fade during the curing period, will reflect more sun reducing the temperature of the concrete during the cure.
Always check that the membrane coating is compatible with anything that will be later applied to the concrete, such as flooring materials.
Further Information
For further information you can check the following websites
Ever wondered how much actual benefit you get from the sun shining in?
How The Sun’s Energy Warms Your Home.
Basically when the suns energy (which includes both visible and invisible energy such as Infra Red and Ultra Violet [UV] radiation) hits your window three things happen to the energy:
Reflection – Plain glass will reflect around 8% of the total energy.
Absorption – 5mm plain glass (the minimum thickness for most domestic windows) will absorb around 12% of the total energy. (Typically around 1/3rd of the energy that is initially absorbed is re-radiated to the inside of your house)
Transmission – The remaining energy, 82% of total energy for 5mm glass will be transmitted into your home.This is known as the RAT Equation
Solar Heat Gain Co-Efficient (SHGC)
Rather than have to keep working through the RAT Equation the glass industry has come up with a Solar Heat Gain Co-Efficient which makes calculations easier.
Values of the SHGC range from 0.82 (5mm float glass) to around 0.15 (double glazing with reflective coatings.
There is more information including SHGC values for a wide range of glazing types at www.nationalglass.com.au
To find the amount of energy coming in through a North facing window you multiply the radiation from the sun by the SHGC.
Winter Example Calculation
For a sunny winters day in Melbourne that the average angle of the sun on the window will be around 20 degrees, so around 800 watts of energy will be falling on each square metre of glass.
The Solar Heat Gain = 8oo watts/m2 x SHGC 0.82 = 652 watts/m2
Assuming that on that sunny winters day the outside temperature is 10 degrees and the internal temperature is 22
Heat loss through the window = 12 degrees x ‘u’ value of 5.8 = 70 watts/m2
Net heating benefit of the window = 652 – 70 = 582 watts / m2.
Summer Evening Example
For a summer evening in Melbourne the average angle of the sun on a window facing the sun will be around 10 degrees, so around 900 watts of energy will be falling on each square metre of glass.
The Solar Heat Gain = 900 watts/m2 x SHGC 0.82 = 738 watts/m2
Assuming that on that summer evening the outside temperature is 35 degrees and the internal temperature, with air conditioning, is 22
Heat gain through the window = 13 degrees x ‘u’ value of 5.8 = 75 watts/m2
Net heating gain of the window = 738 + 75 = 813 watts / m2. (no wonder the air conditioning is working hard!)
Back in November 2009 I thought I would start a blog to record some of the things I have learnt about houses.
I didn’t have any idea where this journey would take me.
Well four years later I suppose I can say I am an Author (even if it still makes me laugh)
If you want to find out more about various key stages in having a house built why not buy a Guide . . . . Warning – Lots of people buying one usually finish up buying more!
All Guides are full of advice for anyone thinking about a new house
I would like to think these are the best selling books, although I don’t really know, but lots of people tell me they are great value . . . . and they are the MOST REASONABLY PRICED!
Moving into a new house may be the time to think about changing your mattress!
Even if its fairly new mattresses looking after it tends to be forgotten so here are some things to think about.
General
Choosing the right mattress is important not only because it determines the quality of sleep but also the mattresses lifespan.
No matter what its size is, a good mattress should be able to serve you for the maximum number of years. This happens only if you take the best care of your mattress.
After reading the below, you will know how to look after your memory foam mattress and when to change it, meaning that you’ll be much more likely to get a great night’s sleep, every night!
Tips On How To Look After Your Mattress
It doesn’t take any special skills to look after your mattress. A few simple actions will ensure that your mattress lasts eight to ten years.
This advice on how to go about it has been tried and tested by many, and will prolong the life of your mattress beyond the usual lifespan.
Use A Cover To Protect Your Mattress
Sleeping directly on the mattress exposes it to stains including hair, dust and dirt which can damage the mattress and shorten its lifespan. Look for a washable mattress (and obviously pillow) covers to protect the mattress such stains.
If you have any allergies then you should buy purpose-made barrier fabric to ward off dust.
Turn Over The Mattress Regularly
Any mattress, no matter what its density is, or how well it is made, wears out due to weight.
If you concentrate weight one on one side or surface then the mattress will wear out irregularly, rendering it uncomfortable or unusable more quickly.
You should turn over the mattress and end to end after every 3 to 4 months, but weekly for the first three months. (This will help the upholstery fillings to settle down more evenly)
Allow The Mattress To Breath
You may not consider it important but those bedclothes you leave on the mattress can limit its lifespan.
One of the best ways to ensure your mattress serves you for the longest time is to take off the bedclothes and allow the mattress to air for at least 20 minutes. This will allow any moisture inside the upholstery to escape.
Keep The Mattress Clean At All Times
Most mattresses can be cleaned by vacuuming. To improve the lifespan of your mattress, you should vacuum it regularly.
If there are stubborn stains, use a cloth with mild detergent and warm or cold water but remember never to soak your mattress.
When To Change Your Mattress
Mattresses are usually hidden under bedclothes or sheets making it difficult to know its condition.
Your mattress needs replacement if:
You feel some stiffness, numbness, aches or pains on your back, neck or other parts of the body.
Your partner tends to toss or turn all night, possibly looking for a more comfortable position and not finding it
You have already used the mattress for more than 7 years without replacement, or your lifestyle or status has changed since your purchase the mattress.
If you find any of the above effects then it may be time to look for a new mattress.
There are so many brands on the market and so you need to be extremely careful to choose the right one that will offer safe, comfortable and quality sleep for longer.
The information above should have equipped you with enough knowledge to look after your mattress and to know when to change it.
This simple practice will save you money and ensure you have high quality sleep.
When the time arrives, you should look for a good replacement from a reputable dealer.