Coastal Building Guide

Building on the Gulf Coast for many years, Thornhill Construction has seen the changes in our community’s codes and floodplains. There are many places where a home could once be built on the ground but now requires a 20 foot plus elevation. Areas like Long Beach, MS, Bay St. Louis, Pass Christian, and Waveland have adopted new codes and floodplains in their entire areas.

In this guide, we hope to show some of the facets of building a home in these coastal areas that as a residential contractor, we face.


Our Guide Will Be Built Into The Following Sections To Keep The Information Organized:

Flood Plain Information –

building along the Mississippi Gulf Coast almost guarantees that you will be trying to determine what your floodplain determination is on your property and how it will impact the style and type of home you build. We have built homes ranging from those that are out of a flood zone and can be built slab on grade to those homes that use piers to get above the current elevation requirements. Learn more by visiting our page on
finding the flood zone for your coastal Mississippi lot.


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  • Building in a floodplain
  • Base flood elevation – BFE
  • Elevated Home FAQ
  • Flood Zones
  • Flood Insurance Once Above The Flood Plain


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Foundations are the bases of our homes, they are what provide us a stable and reliable platform for construction. When they are designed, they are built from durable materials meant to last for many years. In coastal construction, these foundations are what we use to get our homes above the current floodplain requirements. Piers, often made of concrete, like the Coastal Concrete Foundations shown below, raise the height of the foundation as much as 25 feet. Choosing the right foundation layout and specification is key to a strong reliable structure. Concrete foundations are a popular option for getting your home above the current floodplain.

  • Foundations for elevated homes
  • Determining how high

Coastal Construction

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  • Siding or Facia Type – Choosing the right one
  • Rafter tails give the coastal feel
  • Coastal colors and Gulf of Mexico breezes
  • Porches and Outdoor Areas



Building in our communities

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  • Bay St. Louis
  • Diamondhead
  • Gulfport
  • Kiln
  • Long Beach
  • Pass Christian
  • Waveland


Building Beach Homes

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  • These small Mississippi towns are known for being the perfect areas with beaches
  • Sand and an outdoor shower
  • River houses in Mississippi
  • Waterfront homes on MS Coast


When we are building a home, we take years of construction experience to work with us every day to turn out great homes for our families to make memories in. We hope this guide will help walk you through the process of home building with Thornhill Construction.



An eye for detail and style in home construction

Building near a coast is different from building inland. The gulf coast is notorious for getting hit with natural disasters, this is where the coastal building guide comes into play. At Thornhill Construction all of our constructions are built by this guide. The team builds up to code with the intent that you can confidently move into your home. A home built up to the coastal building guide standard is better able to withstand substantial damage from coastal events in addition to lasting longer and reducing maintenance on the home. Another huge benefit of meeting the requirements is lower insurance premiums for the homeowner. It is our goal that every home we build meets or exceeds the requirements set forth by the coastal building guide. We do this with the client in mind, if the home we build is able to withstand most damage caused by coastal forces then it is our chief aim to insure each home is built accordingly. Homebuilders in Bay St. Louis New Home Construction is what we are known for.

There are many builders who choose to build outside of the coastal building code and we are not one of those builders. Our team takes pride in knowing that the homes we build can withstand and endure through much of the coastal events known to cause damage to homes. Thornhill Construction is a company built on integrity; our team are all seasoned on proper building design and materials so that each home we build is a home we can confidently move your family into.

As part of the coastal building guide our team first determines whether the homesite is in Zone A, Zone V, or Coastal Zone A, next an engineer or architect will look at what the Base Flood Elevation is. Many of our homes are built above the Base Flood Elevation to insure no flood water will be pushed into the foundation of the lowest level of the home. All of our homes built with an open foundation, are within code and as such we do not build structures underneath the lowest level of the home. This limits damage caused by flooding and waves in homes built right on or near Zone V. In addition to the foundation and height we choose to build at, the team uses corrosion resistant metals. As Homebuilders in Bay St. Louis New Home Construction It is important to use materials designed to withstand the erosive effects of higher winds and waves which are a known hazard to homes in coastal areas.

Corrosion resistant metals are a source of confusion for many, Thornhill Construction validates each material to make sure we are using truly corrosive resistant metals and we ensure the materials actually are what they are labeled. People are looking for Homebuilders in Bay St. Louis New Home Construction and are glad they found Thornhill Construction. It is imperative to choose like metals especially when building along the coast, metals exposed to coastal erosion must be of corrosive resistant material as they are quicker to erode. Getting insurance is a major reason many homeowners make sure they are up to code. From the materials to the build design, it is imperative that you follow the coastal build guide for both. If you have any questions give our team a call at 228-424-7773. Our staff is well seasoned in all things coastal building and will be happy to assist! Our website is full of information pertinent to custom home building and we encourage you to keep reading at

Looking for Coastal Builders? Then Give Us A Call Today!


Our company chooses to comply with the coastal build guide in order to stay in compliance with the law, but most importantly, we build homes to keep families safe during times of coastal disturbances. A home built to meet or exceed the coastal building guide has reduced maintenance requirements, is more likely to withstand damage caused by coastal events as well as reduced insurance premiums. As the premier coastal builder in the Bay St Louis area our reputation has been what has led us to garner repeat business around the county. Our reputation is built from our high standards we choose to build with. The homes that have Thornhill Construction have a high regard around our community as Homebuilders in Bay St. Louis New Home Construction.

Many people are not familiar with the difference of building inland versus coastal building. There are different factors when building coastal, one of them is the velocities that make coastal flooding much more damaging than inland flooding. The flood levels as well as the wave action are two big factors as well, these two cause greater than inland flooding. The speed of the wind is typically higher when in coastal areas versus inland. Our team is the premier Custom Home Builders Waveland. There is a great concern with coastal erosion which undermines the infrastructure of buildings and roads. The most frequent concerns involve the corrosion from wind driven rain as well as decay. Thornhill Construction has built in the beautiful Bay St. Louis area for the past two decades and have seen their homes stand the test of time by using proper building design and materials. If built according to the coastal building standard homes have longer lifetimes and require less maintenance.

The coastal building guide has many Homebuilders in Bay St. Louis New Home Construction practices that they require for homes built along the coast. The first Homebuilders in Bay St. Louis New Home Construction practice is siting, it is important to first and foremost site the home away from a high hazard area and away from eroding shoreline. This is where the location of the home comes into play, before the building can begin the exact spot must be chosen and it cannot be in a high hazard area or on an eroding shoreline. After the location has been chosen it is time to start designing the home. Many homeowners love high sloped roofs with gable ends or overhangs however it is safest and recommended to avoid these around the home as they are more affected by high winds. The moderate-sloped hip roof is the ideal roof as it does not suffer as much damage during those high winds that are frequent along the coast.

The best way to lower flood insurance premiums is by adding freeboard which reduces damage to the lowest level of the home. Likewise it is important to make the lowest level of the home above the design flood elevation or the base flood elevation. A big thing that our team recommends is to keep the foundation open. We strive to minimize and even avoid using breakaway walls as these lead to increased damage. What we have covered are only a few of the fourteen requirements that we follow from the coastal building guide. Our team is trained and knowledgeable in all of the specifics that come with building along the coast. If you have any questions feel free to call our staff at 228-424-7773. We recommend that we keep perusing our website as we have information, testimonials, and a gallery we have created to give our clients the knowledge they need to confidently build their Custom Home Builders Waveland with us. We are excited to talk to you.