{"id":719,"date":"2014-01-03T16:22:44","date_gmt":"2014-01-03T16:22:44","guid":{"rendered":"http:\/\/bathursthandyman.ca\/?p=719"},"modified":"2014-01-03T16:22:44","modified_gmt":"2014-01-03T16:22:44","slug":"foundation-waterproofing-drainage-mat-blues","status":"publish","type":"post","link":"https:\/\/buildingology.com\/?p=719","title":{"rendered":"Foundation waterproofing drainage mat blues"},"content":{"rendered":"
\"Foundation<\/a>
Foundation drainage mats should never rip.\u00a0 Something is a awry here<\/figcaption><\/figure>\n

I was walking near the government of Canada building on Yonge Street when the grass was still green and found this: \u00a0 A completely torn drainage mat.\u00a0 But is this really a serious problem other than an eyesore?<\/p>\n

The installers of this waterproofing drainage mat layer secured the flashing termination with concrete screws.<\/p>\n

\"IMG-20131105-00035<\/a>
Drainage mat flashing should never bear the weight of the whole mat. The red boxes showed the area that the mat most likely sheared before ripping right below the fasteners<\/figcaption><\/figure>\n

 <\/p>\n

To achieve a nice clean look the termination strip plastic flashing flashing was installed correctly, but er…. someone forgot to fasten the mat below grade with clips.<\/p>\n

Instinct may tell you not to poke holes in your new drainage mat below grade, but with a self adhereing membrane underneath, the nails are self sealing. If you you are still concerned, a sealant can be applied around the fastener, but I don’t think it is necessary.<\/p>\n

\"clips<\/a>
These clips made by Cosella-Dorken have a little plastic rim edge around the fastener location so that any water that passes overtop wound not even touch the nail as shown by red arrows (In theory).\u00a0 The profile of the lip can be seen when looking at the tip of the blue arrow.<\/figcaption><\/figure>\n

 <\/p>\n

Here is the correct way to support the drainage mat, as shown below.\u00a0 The termination strip has not been installed yet in that picture.<\/p>\n

\"the<\/a>
The height of the drainage mat was positioned so that the mat is higher than the grade as a snow covered ground will not wet wall.\u00a0 The orange strip in this mat is helpful in determining the proper position of the mat in comparison to the grade height.<\/figcaption><\/figure>\n

The location of the clips are not critical.\u00a0 It is a good idea to try to not install one directly below a window ledge flashing termination where more water may accumulate.<\/p>\n

So does this mean that the installation with the black mat at the top of the page will do harm?\u00a0 Well maybe to the eyes, yes.\u00a0\u00a0 It depends if there are any fasteners below grade, because those will have ripped too, creating a hole in the mat.\u00a0 But even then, how much water would enter that tear?\u00a0 Keep in mind that the mat covers a large surface area.\u00a0 Another question to ask is how far does the mat slip down?\u00a0 Does it slip down enough to interfere with the weeping tile system?\u00a0 That is a big maybe. It depends on how much settling is taking place.<\/p>\n

How did this happen and what could be done?<\/h2>\n

The soil and\/or gravel backfill does settle, and it is the job of the installers to compact the soil with hand tampers every 1 foot or so.\u00a0 When settling occurs, the mat is pulled down with it, and if there is enough support (using the clips), the soil will settle, but the forces wont be strong enough to tear the mat.\u00a0 The soil would then slide down beside the mat instead of tearing it. \u00a0 There will always be settling, but if there if the soil and gravel was tamped well, then the above scenario may not be a concern at all.\u00a0 Resetting the height of the termination strip may eliminate the eyesore if the mat stops settling.<\/p>\n

\"Buildingology<\/a><\/p>\n