diff --git a/thorlcr/thorutil/thbuf.cpp b/thorlcr/thorutil/thbuf.cpp
index d64d06da1a2..5472c3b7470 100644
--- a/thorlcr/thorutil/thbuf.cpp
+++ b/thorlcr/thorutil/thbuf.cpp
@@ -69,8 +69,8 @@ class CSmartRowBuffer: public CSimpleInterface, implements ISmartRowBuffer, impl
     ThorRowQueue *in;
     size32_t insz;
     ThorRowQueue *out;
-    Linked<IFile> file;
-    Owned<IFileIO> fileio;
+    CFileOwner tmpFileOwner;
+    Owned<IFileIO> tempFileIO;
     SpinLock lock;
     bool waiting;
     Semaphore waitsem;
@@ -139,12 +139,12 @@ class CSmartRowBuffer: public CSimpleInterface, implements ISmartRowBuffer, impl
             insz = 0;
             return;
         }
-        if (!fileio) {
+        if (!tempFileIO) {
             SpinUnblock unblock(lock);
-            fileio.setown(file->open(IFOcreaterw));
-            if (!fileio)
+            tempFileIO.setown(tmpFileOwner.queryIFile().open(IFOcreaterw));
+            if (!tempFileIO)
             {
-                throw MakeStringException(-1,"CSmartRowBuffer::flush cannot write file %s",file->queryFilename());
+                throw MakeStringException(-1,"CSmartRowBuffer::flush cannot write file %s",tmpFileOwner.queryIFile().queryFilename());
             }
         }
         MemoryBuffer mb;
@@ -182,7 +182,8 @@ class CSmartRowBuffer: public CSimpleInterface, implements ISmartRowBuffer, impl
                 size32_t left = nb*blocksize-mb.length();
                 memset(mb.reserve(left),0,left);
             }
-            fileio->write(blk*(offset_t)blocksize,mb.length(),mb.bufferBase());
+            tempFileIO->write(blk*(offset_t)blocksize,mb.length(),mb.bufferBase());
+            tmpFileOwner.noteSize(numblocks*blocksize);
             mb.clear();
         }
         if (waiting) {
@@ -220,8 +221,8 @@ class CSmartRowBuffer: public CSimpleInterface, implements ISmartRowBuffer, impl
             size32_t readBlockSize = nb*blocksize;
             byte *buf = (byte *)ma.allocate(readBlockSize);
             CThorStreamDeserializerSource ds(readBlockSize,buf);
-            assertex(fileio.get());
-            size32_t rd = fileio->read(blk*(offset_t)blocksize,readBlockSize,buf);
+            assertex(tempFileIO.get());
+            size32_t rd = tempFileIO->read(blk*(offset_t)blocksize,readBlockSize,buf);
             assertex(rd==readBlockSize);
             for (;;) {
                 byte b;
@@ -246,8 +247,8 @@ class CSmartRowBuffer: public CSimpleInterface, implements ISmartRowBuffer, impl
 public:
     IMPLEMENT_IINTERFACE_USING(CSimpleInterface);
 
-    CSmartRowBuffer(CActivityBase *_activity, IFile *_file,size32_t bufsize,IThorRowInterfaces *rowif)
-        : activity(_activity), file(_file), allocator(rowif->queryRowAllocator()), serializer(rowif->queryRowSerializer()), deserializer(rowif->queryRowDeserializer())
+    CSmartRowBuffer(CActivityBase *_activity,IFile *_file,size32_t bufsize,IThorRowInterfaces *rowif)
+        : activity(_activity), tmpFileOwner(_file, _activity->queryTempFileSizeTracker()), allocator(rowif->queryRowAllocator()), serializer(rowif->queryRowSerializer()), deserializer(rowif->queryRowDeserializer())
     {
 #ifdef _DEBUG
         putrecheck = false;
@@ -282,11 +283,8 @@ class CSmartRowBuffer: public CSimpleInterface, implements ISmartRowBuffer, impl
         while (out->ordinality()) 
             ReleaseThorRow(out->dequeue());
         delete out;
-        if (fileio)
-        {
-            fileio.clear();
-            file->remove();
-        }
+        if (tempFileIO)
+            tempFileIO.clear();
     }
 
     void putRow(const void *row)
@@ -1197,8 +1195,8 @@ bool CRowSet::Release() const
 
 class CSharedWriteAheadDisk : public CSharedWriteAheadBase
 {
-    Owned<IFile> spillFile;
-    Owned<IFileIO> spillFileIO;
+    Owned<CFileOwner> tempFileOwner;
+    Owned<IFileIO> tempFileIO;
     CIArrayOf<Chunk> freeChunks;
     PointerArrayOf<Chunk> freeChunksSized;
     QueueOf<Chunk, false> savedChunks;
@@ -1420,7 +1418,7 @@ class CSharedWriteAheadDisk : public CSharedWriteAheadBase
         }
         else
         {
-            Owned<ISerialStream> stream = createFileSerialStream(spillFileIO, chunk.offset);
+            Owned<ISerialStream> stream = createFileSerialStream(tempFileIO, chunk.offset);
 #ifdef TRACE_WRITEAHEAD
             unsigned diskChunkNum;
             stream->get(sizeof(diskChunkNum), &diskChunkNum);
@@ -1484,7 +1482,8 @@ class CSharedWriteAheadDisk : public CSharedWriteAheadBase
             mb.append((byte)0);
             size32_t len = mb.length();
             chunk.setown(getOutOffset(len)); // will find space for 'len', might be bigger if from free list
-            spillFileIO->write(chunk->offset, len, mb.toByteArray());
+            tempFileIO->write(chunk->offset, len, mb.toByteArray());
+            tempFileOwner->noteSize(highOffset);
 #ifdef TRACE_WRITEAHEAD
             ActPrintLogEx(&activity->queryContainer(), thorlog_all, MCdebugProgress, "Flushed chunk = %d (savedChunks pos=%d), writeOffset = %" I64F "d, writeSize = %d", inMemRows->queryChunk(), savedChunks.ordinality(), chunk->offset, len);
 #endif
@@ -1507,16 +1506,15 @@ class CSharedWriteAheadDisk : public CSharedWriteAheadBase
         allocator(rowIf->queryRowAllocator()), deserializer(rowIf->queryRowDeserializer()), serializeMeta(meta->querySerializedDiskMeta())
     {
         assertex(spillName);
-        spillFile.setown(createIFile(spillName));
-        spillFile->setShareMode(IFSHnone);
-        spillFileIO.setown(spillFile->open(IFOcreaterw));
+        Owned<IFile> iFile = createIFile(spillName);
+        iFile->setShareMode(IFSHnone);
+        tempFileIO.setown(iFile->open(IFOcreaterw));
+        tempFileOwner.setown(new CFileOwner(iFile.getClear(), activity->queryTempFileSizeTracker()));
         highOffset = 0;
     }
     ~CSharedWriteAheadDisk()
     {
-        spillFileIO.clear();
-        if (spillFile)
-            spillFile->remove();
+        tempFileIO.clear();
 
         for (;;)
         {
@@ -1536,7 +1534,8 @@ class CSharedWriteAheadDisk : public CSharedWriteAheadBase
         freeChunks.kill();
         freeChunksSized.kill();
         highOffset = 0;
-        spillFileIO->setSize(0);
+        tempFileIO->setSize(0);
+        tempFileOwner->noteSize(0);
     }
 };