Category: Tips & Tricks

When designing site drainage, do you even need an ag pipe?

Big hint: Water flows through gravel without an ag pipe.

Here’s the order of the universe:

Gravel – Highly porous with large particle sizes that allow water and air to pass through easily.

Coarse Sand – Very porous, with relatively large particles and low water retention.

Fine Sand – Moderately porous, smaller particles than coarse sand but still allows significant drainage.

Loamy Sand – A mix of sand and some silt and clay, moderately porous but retains more water than pure sand.

Loam – A balanced mix of sand, silt, and clay, providing moderate porosity and good water retention.

Silt – Less porous than loam, with smaller particles that retain water well but drain more slowly.

Sandy Clay Loam – Less porous, with a higher clay content that reduces permeability.

Clay Loam – Low porosity due to a high clay content, retaining water more effectively.

Clay – Least porous, with very small particles that make drainage extremely slow and retain water tightly.

So before you shell out the money for an ag pipe, take a minute to determine what you are trying to achieve.

We’ve said it before and we’ll say it again: Ag pipes don’t magically make water flow uphill!

• Grade the base of your drainage trench in the direction you want water to flow.
• Use a geofabric (or not – it’s up to you) to minimise silt loading.
• Use 10mm or 20mm gravel in your drainage trench to allow water to flow down the hill/grade.
• Discharge water without causing a nuisance to your neighbours.

Water that sits in gravel-filled trenches also soaks into the ground. It doesn’t ALL drain down the hill. Think about where you position your drainage trench and the effect of water soaking into your ground.

Best of luck!

Water Ingress or Site Drainage Problems? Take Action Now!

If you’re dealing with water ingress or site drainage issues, you probably already know the problem isn’t going to fix itself. Like the boy who stuck his finger in the dike, the key is taking action.

What you don’t need is another quote, another opinion, or another lengthy report gathering dust. What you do need is to act decisively.

Sometimes, the first solution doesn’t fully solve the problem—that’s just part of the process. But every step you take brings you closer to a lasting fix. Waiting only makes the issue worse.

Let’s stop the water in its tracks.

If you’re ready to take the next step, contact us today.

Builders stop reading plans when engineers issue poor-quality drawings. Then, when things go wrong, builders have no explanation for the failure.

How about this: make your engineers provide what they were engaged to do.

READ THE PLANS.

If engineers issue poor-quality plans (or reports) send them back to be fixed. Force your engineer to provide what they were engaged to do.

Builders: stop carrying the risk of poor-quality plans.

1. Read the plans.

2. Ask lots of questions.

3. Get errors and missing information fixed.

Put the risk back on your professional engineer. You paid an engineer so you have someone to blame. Get your money’s worth!

(First published on Cornell Engineer’s Facebook Page)

DIY Drainage Inspection for Sloping Sites: A Homeowner’s Checklist

Dealing with water entry issues in homes on sloping sites can be tricky, but catching problems early can save you time, stress, and money. Use this step-by-step checklist to identify potential drainage issues around your property.

1. Observe Water Flow During Rain

Walk around your property during a heavy rainstorm or immediately afterwards.

Identify where water is pooling, flowing, or draining too slowly.

Check for water running towards your home rather than away from it.

2. Inspect Gutters and Downpipes

Ensure gutters are free of leaves and debris.

Confirm downpipes are connected to the stormwater system.

Check if downpipes discharge water well away from the house (downstream).

3. Assess the Ground Slope

Does the ground slope away from your home on all sides? If not:

Look for areas where water could flow toward the foundation or basement.

Note any signs of erosion or sediment build-up near walls.

4. Check Retaining Walls

Inspect retaining walls for signs of water seepage, efflorescence (white powdery residue), or cracks.

Look behind retaining walls for gravel backfill and ensure it hasn’t compacted or clogged over time.

Note if water seems to pool in trenches near walls.

5. Examine Basement or Ground-Level Walls

Look for damp spots, peeling paint, or mould inside your basement or lower rooms.

Check for water stains or musty odours, which may indicate hidden water entry.

Inspect the base of walls for visible water seepage.

6. Evaluate Surface Drainage Solutions

Look for spoon drains, field inlet pits, or other drainage features.

Check if they are clear of debris and functioning correctly.

Ensure water from these systems is directed well away from the house.

7. Test Soil and Drainage

Observe if water takes a long time to drain from the soil after rainfall.

Note if your property has sandy soil over clay, which can allow water to run towards the house.

Check for any exposed clay or compacted areas that might redirect water.

8. Inspect Neighbouring Properties

Look over fences or use aerial maps to assess if water might flow onto your property from upslope neighbours.

Identify potential overland flow paths from nearby properties that could impact yours.

9. Identify Common Problem Areas

Blocked gutters and insufficient downpipes.

Poorly graded ground near the foundation.

Trenches or gravel backfill holding water near walls.

Roof water discharging into ag pipes or ground uphill of the house.

10. Plan Next Steps

For minor issues, consider DIY fixes like regrading soil or clearing gutters.

For larger problems, such as water seepage into walls or significant pooling, consult a structural engineer or drainage specialist.

By following this checklist, you can gain insight into how water interacts with your property and identify areas that need improvement.

A little proactive inspection can go a long way in protecting your home from drainage issues.

A big thank you to Georgina and her family for asking Cornell Engineers to provide structural engineering for their home renovation (house raise and build in under project) in Milton.

We asked Georgina five questions about the process so far (design and documentation stage). Here’s what Georgina had to say!

It’s early days in your house renovation project so far. What obstacles and problems have you had to solve already that you didn’t expect? Have you overcome those problems yet? 

We really wanted to have some off street parking but without lifting or moving the house it wasn’t possible. We made the decision to leave that given the budget required was too much. 

We also want a pool, this was going to be an issue with the slope of the land and stormwater drains plus the limited access we have at our property. Luckily we have found a position for the pool that suits and digging for the pool can be done early on in the project when we have excavators on site. I’m sure there will be more obstacles that pop up along the way but so far so good! 

What were the critical factors in the decision to stay and renovate instead of selling and buying a different house?

We did have a good look at the market and went to inspect quite a few houses before we made the decision to renovate.

All the properties we looked at were good but always with issues that would have to be fixed with a small renovation anyway or not in a great location. We decided in the end that being able to work with what we had already to create a home that is perfect for us.

What is the thing you love most about your house pre-renovation? What do you think you will love most when the renovation is complete? 

We love our street & also the beautiful view from our back deck. I will love having more than 1 bathroom with teenage boys in the house!

Where have you drawn inspiration from for your renovation? How did you have to modify those thoughts to keep the project within budget and comply with the approval process?

We have drawn inspiration from other properties in the area and really thought about what we needed as a family, especially with our children getting older. The need for some separate living spaces especially…

We have tried to keep the project within budget by considering the use of different, more cost-efficient products in the tiling and flooring of the property. We also had a few ideas early on in the planning process that we have cut from the project. The approval process was actually quite easy given the fact we were very happy to keep the existing style of the house.

What is your key piece of advice to other homeowners thinking about renovating their homes? 

Be patient, do your research and try to find a good team that you can trust to listen to your needs and get the job done!

Thank you Georgina

Thank you very much Georgina for taking the time to bring us up to speed on your home renovation in Milton. We look forward to seeing more projects like this beautiful home renovation!