Index: binaries/data/mods/public/simulation/components/Foundation.js
===================================================================
--- binaries/data/mods/public/simulation/components/Foundation.js
+++ binaries/data/mods/public/simulation/components/Foundation.js
@@ -1,7 +1,9 @@
 function Foundation() {}
 
 Foundation.prototype.Schema =
-	"<empty/>";
+	"<element name='DiminishingReturns' a:help='Effect for having multiple builders.'>" +
+		"<ref name='nonNegativeDecimal'/>" +
+	"</element>";
 
 Foundation.prototype.Init = function()
 {
@@ -15,7 +17,6 @@
 	this.builders = new Map(); // Map of builder entities to their work per second
 	this.totalBuilderRate = 0; // Total amount of work the builders do each second
 	this.buildMultiplier = 1; // Multiplier for the amount of work builders do
-	this.buildTimePenalty = 0.7; // Penalty for having multiple builders
 
 	this.previewEntity = INVALID_ENTITY;
 };
@@ -235,7 +236,7 @@
 Foundation.prototype.CalculateBuildMultiplier = function(num)
 {
 	// Avoid division by zero, in particular 0/0 = NaN which isn't reliably serialized
-	return num < 2 ? 1 : Math.pow(num, this.buildTimePenalty) / num;
+	return num < 2 ? 1 : Math.pow(num, +this.template.DiminishingReturns) / num;
 };
 
 Foundation.prototype.SetBuildMultiplier = function()
Index: binaries/data/mods/public/simulation/templates/special/filter/foundation.xml
===================================================================
--- binaries/data/mods/public/simulation/templates/special/filter/foundation.xml
+++ binaries/data/mods/public/simulation/templates/special/filter/foundation.xml
@@ -8,7 +8,9 @@
   <Fogging merge=""/>
   <Footprint merge=""/>
   <!-- Add the Foundation component, to deal with the construction process. -->
-  <Foundation replace=""/>
+  <Foundation replace="">
+    <DiminishingReturns>0.7</DiminishingReturns>
+  </Foundation>
   <Health>
     <Initial>1</Initial>
   </Health>