Potential impact of wetland on a property?

Question: We are about to make an offer on a house, and just found out that the property is partially built on a piece of wetland. Is there a significant negative impact? House was built in 1993.

Answer:  Here’s some context before diving into the specific situation:
a) Wetlands can have impact based on category of wetland – low category are safer with less impact. Higher category are not, and thus permissions to build homes are not given by the city for this category.
b) When a house is built on a wetland, it has to first go through a thorough study/evaluation by city – which includes an in-depth staff research, site visit, home design study, land digging etc. Only after the home and site pass this thorough evaluation, a house is allowed to be built. 

In this case, if city had given permission to build the house, then the initial study must have revealed that the wetland will not have any negative impact on the house, and all the drainage systems in place/planned are adequate and approved by the city.

However, it is quite possible that there is actually some negative impact of being on the wetland, which was not anticipated in the initial evaluation/study. This impact can be known by a home inspection. Since, the house was built in 1993, more than 25 years ago, it has been through the test of time. Any negative impact of wetland would likely start showing up by now. So an inspection must be done on the house to check any impact of the wetland. Crawlspace and foundation will be the first areas to show any negative impact, mainly moisture building, or settling. Hence, the inspector should pay specific attention to these items, and also to the drainage. Inspector will be able to tell if wetland has any negative impact on the house, or not.

One negative aspect of house built on wetland is that it can limit doing additions on the house i.e. adding square footage, or extra room. It is much easier to do these additions on normal lands (non-wetland) than on wetlands.

This is because, if an addition is done, then wetland can have negative impact on the newer part built and thus on the house. So do check with sellers if they made any modification/additions to the house, which impacted the area on which the dwelling is built. You can also check with the listing agent, if owners have any report about the wetland (since the owners are first owners, so they might have got this from the builders).

So overall, if there is an impact on the house it would show up in inspection. Be aware that doing additions on property would be tougher or even not possible. Do check with sellers if they did any modifications/additions to the house during their ownership, and have any information from builders about wetland.


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